Bluetooth file transfer randomly fails. Why?!

D

DaRuSsIaMaN

[H]ard|Gawd
Joined
Apr 22, 2007
Messages
1,216
I get so angry....

Without any apparent reason or consistency, sometimes my phone refuses to send files to my laptop over BT. Simply tells me that it didn't send, or something to that effect. I have never had any issue sending or receiving files between my laptop and my tablet, for example.

Laptop: Win 10
Tablet: Win 8.1
Phone: Android

Anyone have any explanation? I think I would even be less angry if it always failed. At least then it would be consistent... But this randomness without any plausible explanation drives me absolutely insane. Would greatly appreciate any pointers.
 
Bluetooth is shit for actual file transfers, first and foremost. There are so many levels of the Bluetooth certification standard that the chances of you finding two perfectly compatible devices that will talk with each other at proper but still fucking slow as hell speeds is pretty non-existent. I recently owned a rather nice combo Wi-Fi/Bluetooth card that I placed in my laptop (Dell Latitude E6420) and went through a lot of shit to find the proper Bluetooth drivers (had to go to Broadcom's website eventually and just get their "official" Widcomm Bluetooth stack) and even after all that shit and knowing I had two Bluetooth 4.0 capable cards that supposedly were "HS" aka High Speed certified they would never ever communicate with each other properly and transfer speeds were the same old lame ass barely 175KB/s that most any old Bluetooth 3.0 or higher hardware is capable of.

Long story short: stop using Bluetooth for file transfers and save yourself a lot of hassles, BS, and of course actual time. There are tons of tools available to do Wi-Fi based transfers nowadays, from Wi-Fi Direct (which is damned fast indeed if you have two dual band 11n or 11ac devices, probably won't get anything faster than this method of transfer) There's an app on Android that I just started using last week called Send Anywhere and it's very useful especially for Android to Android transfers using Wi-Fi Direct but I've been using WiFi File Transfer Pro for years now and it's been my go-to app to move files wirelessly (when necessary meaning when it's not convenient to use the USB cable) and it's always been good to me so that's the tool I recommend the most for actual wireless data transfer from an Android device to a PC.

There are tons and tons of other such apps as well, but do yourself a favor and just stop trying to get Bluetooth to be useful for file transfers. That capability was meant to be used to transfer very small files like emails/small documents/contact information and other very small items that are usually smaller than even one JPG image so, time-out problems are more likely to happen by attempting to transfer large files bigger than even 100KB.

I would, however, suggest that you see if those "official" Broadcom Widcomm drivers and the Widcomm stack might improve things for you. The default Bluetooth drivers for most laptops are built into Windows, supplied by Microsoft, and they are far far from efficient or reliable. The Widcomm stack is generally considered to be "the best" you're going to find for that purpose, even more so than the drivers supplied by the maker of the given Bluetooth card or device, actually. Some will use Broadcom drivers but the manufacturer supplied ones are almost always way way out of date so, the "official" Broadcom stack is highly recommended and you can find it here:

https://www.techspot.com/drivers/driver/file/information/16339/

Note that Broadcom itself does not supply the Widcomm stack any more, but that one at that link is "safe" and it's the last one they released publicly and the one I use and recommend so, it might help your situation, it might not. It might not even install if you attempt it because it'll check to see if your hardware is OK to go, some low quality manufacturers use non-standard BT chipsets so, it can't hurt to at least try that Widcomm stack and see if it helps.

And yes, one big reason for Bluetooth being so unreliable for large file transfers aka anything literally over 100KB in size, is radio interference aka EMI. Because Bluetooth is by nature a low power radio signal (not to be confused with the newer BT standard known as LE or Low Energy which is a different technology than I'm speaking of) that means it's not capable of "punching through" all the typical interference associated with using the 2.4 GHz radio band which is where BT/GPS/Wi-Fi and many other types of devices now try to fight for every little bit of bandwidth they can. In a heavy signal laden Wi-Fi area that will wreck Bluetooth comms of most any and all kinds.

Some Wi-Fi and Bluetooth adapters have a setting you can adjust for better compatibility so the two aspects work better together but even so, the recommendation is stop using Bluetooth for transferring anything but really small files and use Wi-Fi in some manner and you'll be vastly better off.
 
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Sorry about taking forever to get back to this and reply. (It wasn't a super urgent issue...) Tiberian, thanks so much for your detailed reply! Definitely makes me feel better to know that I'm not the only one suffering from random problems with trying to get these things to talk to each other... As they say, misery loves company lol.

Also, I really thought that BT was SUPPOSED to work for such purposes. So I was getting frustrated that it wasn't working for me. But if you're telling me it was never even intended for this kind of usage (like sending photos from my phone wirelessly), and that I should expect it to be shitty, then yeah, I'll definitely just stop banging my head against the wall with this. I'll go ahead and explore whatever other alternative to BT exists.

Regarding wi-fi direct. I did explore that (a bit) previously on my old phone, before I switched to this one. I tried a couple apps, SuperBeam, and there was one other one that I forgot the name of. IIRC, both of them worked great for file transfer from phone to PC at home, but refused to work when I was on my university campus. I don't understand it... it seemed that they somehow needed to connect to the wi-fi network that I'm using. But how does that make sense? Isn't the whole point of the technology that you get to bypass the router that provides the wi-fi and have the two devices talk to each other directly?? Is it because the direct connection only works Android to Android, but not Android to PC?

Anyway, I did just experiment with transferring files from phone to laptop using AirDroid. I've had this app/software installed for a few months now, only experimented with it a bit. It actually worked fine for transferring a couple photos. I don't think it uses wi-fi direct, though, pretty sure it sends data "the long way", like the same way that my data from my phone normally travels, which would explain why I have to log in with a username/password into the AirDroid PC program.

I'm gonna look into your recommendation, WiFi file transfer pro. Thanks!
 
Realize that when Bluetooth first came out most if not all phones didn't have a camera, of any kind, so that wasn't the purpose (sending pictures). The purpose was short range wireless connectivity for the transfer of very simplistic data like contact info from one client to another, address info, business related stuff, literally just small text files and not really much more. As cameras started being added to phones - they hadn't even gotten to the smartphone stage yet, I'm talking some of the first Palm-enabled and Windows Mobile-enabled stuff (long before Windows Phone came along) with stuff like half-megapixel shooters in them. A half-megapixel shooter will end up producing a JPG image that's under 100KB in size which, as I mentioned earlier, is about the basic practical and effective limit for a good solid Bluetooth transfer to handle, maybe up to about 200KB reliably.

But nowadays, with smartphones having 13, 16, 20, 24, and even more megapixels the size of the images now is crazy: I can take a pic with my V10 and the 16 Megapixel camera and then be left with a 100% quality JPG file that's 5-8MB in size so you can see that's a pretty huge jump in the amount of data you'd need to transmit. Think of Bluetooth file transfers as "hey, we can send <so much per second> so as long as the file fits inside that one second, maybe 2 or 3 at most, that's what you should consider to be the limitation."

For big freakin' files, that's what WiFi is for and also as noted there are a ton of WiFi file transfer apps out there for every platform (Android, iOS, whatever). And yes, WiFi Direct is a point to point wireless connection so device 1 connects and communicates with device 2 and that's it, no access point/router/hub/etc necessary and it can be seriously fast when it works right.

As for connection issues, most public or private WiFi connections and networks use firewalls for their own security and point to point file transfers on the same network can be detected as malware/virus-like - I'm not saying it is, just that it can be seen by the firewall as that kind of activity since that's how malware/virus crap spreads, it infects one machine then spreads. So that is the most likely reason you'd have issues using WiFi related point to point file transfers on the same network, I've had such issues myself in many public places with hotspots, like hospitals and airports, it's not an uncommon problem really.
 
Tiberian said:
For big freakin' files, that's what WiFi is for and also as noted there are a ton of WiFi file transfer apps out there for every platform (Android, iOS, whatever). And yes, WiFi Direct is a point to point wireless connection so device 1 connects and communicates with device 2 and that's it, no access point/router/hub/etc necessary and it can be seriously fast when it works right.

As for connection issues, most public or private WiFi connections and networks use firewalls for their own security and point to point file transfers on the same network can be detected as malware/virus-like - I'm not saying it is, just that it can be seen by the firewall as that kind of activity since that's how malware/virus crap spreads, it infects one machine then spreads. So that is the most likely reason you'd have issues using WiFi related point to point file transfers on the same network, I've had such issues myself in many public places with hotspots, like hospitals and airports, it's not an uncommon problem really.
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But I don't understand -- if WiFi Direct does not need access point/router/etc, then why would the local WiFi network have any ability to interfere with it? Why would the public WiFi network even be "aware" of my two devices communicating via WiFi direct? If the two devices are bypassing the router, then their data is not using the ambient WiFi network at all, right? So there shouldn't be any issues regardless of what security rules the network has in place...
 
No, that's not why using a public or even a private hotspot might cause a problem. Look at it this way, maybe it'll help, and the relevant part of my statement you quoted is basically this part: "... WiFi related point to point file transfers on the same network ..." and it's the "on the same network" part that contains the most important aspect: on the same network you can and most likely will have problems, but WiFi Direct is point to point, not really a network of devices overall as networks are commonly understood.

To use an actual Access Point or hotspot with two devices connected to it the data has to go from (for this example) device A to device B, with the access point/hotspot/router being "the middleman" in the connection - all the data has to flow through "the middleman" to go anywhere. Now, "the middleman" can and often does have a firewall with specific rules in place and sometimes those rules prevent data from flowing over it meaning between two devices on the same network. This is done more as a security issue more than anything else; it's well known that on a network a virus will hop device to device on the same network so most commercial AP/hotspot hardware actually has firewall rules in place that prevent such connections from happening.

So while device A can connect to the AP/hotspot, and device B can connect to the same AP/hotspot, once connected the two devices can't (more often than not) directly communicate over that local network for that specific reason. They can connect to each other using the Internet aspect meaning if you connected to some chat or IM client with device A, and then did the same thing with device B (a different account obviously) the two devices could communicate through the router at that point because the traffic is going outbound and inbound from the AP/hotspot itself and not over it using local IP addresses.

I know that might be more complicated than it needs to be but it's the best description I can provide at this moment.

Using WiFi direct, no AP/hotspot is required, device A and device B would connect to each other directly (yes, I know, silly but true) point to point with no "middleman" anywhere in the circuit. There have been many times where I'll connect to an AP/hotspot in a hospital or airport or some other place and my wife connects to it as well and I get frustrated because I'm not able to send her pics or whatever directly between the two devices over that wireless network we connect with. My particular smartphone has WiFi Direct support but hers doesn't so, I have to send a pic or whatever through our chat/IM clients (we use Hangouts) and if for some reason that doesn't work then I'll upload it to my Drive account then share the link for her to get it.

tl;dr If you have two devices connecting to a public/private AP/hotspot there's a chance the two devices won't be able to see each other directly nor communicate directly over that wireless LAN (hence, WLAN, the acronym for wireless local area networks) - it's the middleman aspect with the firewall in the AP/hotspot that typically prevents such activity. If, however you use WiFi Direct you are NOT connecting to the AP/hotspot or middleman and don't have such issues.

Got it? I'm pretty sure you did before I even made this post but, can't hurt to be thorough even so. :D
 
Tiberian said:
I know that might be more complicated than it needs to be but it's the best description I can provide at this moment.
Click to expand...

No, I don't think it's complicated, and that's basically how I thought it worked. I imagined the information flow to be analogous to streets leading to and from an intersection: like, you can drive out of your house (A) onto the street, get to the intersection, and then turn into another street and arrive at another nearby house (B). But you can't directly drive from house A to house B because then you'd be plowing through peoples' backyards. The router/AP in this analogy would be like the intersection and streetlight guiding traffic, while the streets themselves are the radio waves beamed out by the router. The "streets" only reach as far as the signal strength is not too weak.

Anyway, I thought that I previously tried one or two apps that were WiFi Direct. And I tried to use the app to send files between my laptop and phone. (I had the app installed on phone, and the PC version on laptop.) And it seemed that it refused to work at my university. Hence, it seemed as if the hotspot network was interfering somehow... but why the hell are those devices interacting with the "middleman" in the first place? If they're WiFi direct apps, they should not be interacting with the hotspot network in any way.
 
Because they're not WiFi Direct apps - WiFi Direct doesn't require any apps, it's part of Android now on most devices (and on other platforms as well like iOS which I think does support it, and of course desktop and laptop hardware depending on manufacturer support in the wireless drivers) and an option either under the WiFi options menu(s) or perhaps the "Sharing" or anything related to sharing data (not tethering, however, which is a different thing altogether anyway).

All those apps on the Play Market that make claims of "WiFi direct connection" don't actually use WiFi Direct which is a spec Intel helped create years ago but it never really caught on for a variety of reasons - the massive proliferation of so many access points and hotspots is part of that reason, WiFI is ubiquitous now most anywhere so, it's easier for most folks to use an access point first and foremost but then you encounter the firewall issues depending on how the AP/hotspot is locked down.

But I'm just rambling on now, you got it the first time out as I suspected so, "It's Saul Goodman..." as the saying and the TV show goes. :)
 
Well, not really because some Wi-Fi hardware used in desktops and laptops - almost always specifically being Intel wireless hardware since they designed the Wi-Fi Direct spec to begin with - can support Wi-Fi Direct connections. I have an Intel Centrino "Ultimate-N" 6300 Wi-Fi card in my Latitude laptop and it supports Wi-Fi Direct but the issue for me is making that functionality work. I don't use Intel's Wi-Fi software tools which is why I don't have the usage of Wi-Fi Direct, all I ever use for wireless hardware are the drivers so the OS can make use of the hardware device and functionality, that's all I require.

Having said that, IF I install the Intel wireless software I'd be able to make use of Wi-Fi Direct between my smartphone (an LG Stylo 2 Plus) and the laptop and that would work fine but since they're both already on the same wireless router and they're both connected to the router at ~300 Mbps then there's no point for me to just add more crap in the data path with more software and whatever, that's what I purchased WiFi File Transfer Pro for years ago and have never had any issues with it. The browser-based interface that app provides is pretty simple, it gets the job done, and I simply don't require anything else.

So, if you're like me and you only install the drivers for your wireless hardware in your desktop or laptop computer you're not going to get the Wi-Fi Direct functionality, that aspect requires the full software package - assuming the card supports Wi-Fi Direct, of course - to be able to make use of that capability. Windows itself (any version) doesn't offer Wi-Fi Direct as part of the native wireless controls either, but you can do something like an ad-hoc infrastructure mode connection peer to peer, I've only done that one time in the past decade and it was so problematic to get it working properly I never bothered with it again.

Short short version: if your desktop or laptop wireless hardware is capable of Wi-Fi Direct operation, you'll need to install the full software package and the manufacturer's wireless client application(s) to make use of it because Windows by default has no such capability to make use of Wi-Fi Direct natively.
 
Tiberian said:
Short short version: if your desktop or laptop wireless hardware is capable of Wi-Fi Direct operation, you'll need to install the full software package and the manufacturer's wireless client application(s) to make use of it because Windows by default has no such capability to make use of Wi-Fi Direct natively.
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Wow, I just came back to this thread and re-read it again because I got a new smartphone and am reinstalling apps. Looks like I forgot to reply to your last post. So thanks again for the very informative help!
 
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