CAUTION: APC UPS breaks Ethernet over power line

philb2

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May 26, 2021
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A tale of caution.

I have this pair of old Netgear power line adapters. So I used these adapters to put my HP 401 printer on the home LAN. Life was good again.

Until I noticed that one of the power line connectors was not connected to a UPS (which protects my cable modem and some other gear). So I plugged the powerline connector into a power strip connected to the UPS. Uh oh.Then life wasn't so good. I couldn't get the pair of powerline connectors to recognize each other. (This looks bad on front of my wife, when I had told her, "No problem, it will take just a minute.") 30 minutes later, duuuuuuuuh, it occurred to me that I needed to plug the powerline connector directly into a wall outlet.

Presto! Now the power line adapters work the way they are supposed to, and life has become good again.
 

Nenu

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Think of an UPS like a filter for anything passing through it.
Then think what a filter can do.

The UPS didnt break ethernet over power line.
The UPS prevented the mains ethernet signal passing through the UPS, not a surprise (though some UPS may not have this problem unless mains is down), a significant difference.
It didnt affect the mains ethernet signal outside of the UPS, you cannot generically say "APC UPS breaks Ethernet over power line".
 

philb2

Gawd
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Think of an UPS like a filter for anything passing through it.
Then think what a filter can do.

The UPS didnt break ethernet over power line.
The UPS prevented the mains ethernet signal passing through the UPS, not a surprise (though some UPS may not have this problem unless mains is down), a significant difference.
It didnt affect the mains ethernet signal outside of the UPS, you cannot generically say "APC UPS breaks Ethernet over power line".
Ok I stand corrected. The UPS filters stopped the Ethernet signal. From a "black box" point of view, the UPS did break the "functioning" of the Ethernet over power line devices.
 

jmilcher

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Most of the power line adapter directions specifically say not to use them directly with a UPS. And most say not to with a surge protector. In your case you did both.

Really they are designed to be right on the outlet.

I don’t think this is a PSA situation. This is a didn’t RTFM situation.
 
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Zepher

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Ok I stand corrected. The UPS filters stopped the Ethernet signal. From a "black box" point of view, the UPS did break the "functioning" of the Ethernet over power line devices.
No, it didn't not break it, that would say that it worked while connected through the UPS and then stopped working.
 

philb2

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I don’t think this is a PSA situation. This is a didn’t RTFM situation.
jmilcher

True enough. But I did RTFM. Which was silent on the question of connecting through a power strip or UPS.

I make it a point to download the manual for damn near everything in my house. PCs, laptops, disk drives, video cards, printers, cable modems,etc. All appliances, cars, TVs, cameras, smoke and CO2 detectors, everything. Having it all on my system, sorted out of course, is a huge time-saver. Totally worth the effort.
 
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jmilcher

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jmilcher

True enough. But I did RTFM. Which was silent on the question of connecting through a power strip or UPS.

I make it a point to download the manual for damn near everything in my house. PCs, laptops, disk drives, video cards, printers, cable modems,etc. All appliances, cars, TVs, cameras, smoke and CO2 detectors, everything. Having it all on my system, sorted out of course, is a huge time-saver. Totally worth the effort.
I didn’t look up your specific model. I do know from reading the manual in the 3 brands I own or have installed, that all mentioned not to do this. Just an assumption on my part admittedly. Glad you got it figured out tho.
 

philb2

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I didn’t look up your specific model. I do know from reading the manual in the 3 brands I own or have installed, that all mentioned not to do this. Just an assumption on my part admittedly. Glad you got it figured out tho.
I did get it all figured out. So all is good again.

I didn't actually buy this part of powerline adapters, nor have I even shopped for any. Comcast installed them with an earlier home security setup. Then they replaced the home security controller and didn't use these powerline adapters, so I figured I may as well use them. When Comcast installed these adapters, they plugged them in to wall outlets. I'm sure that Comcast didn't spend a wooden nickel more than they needed to for these units.

They are OK, but a bit slow. When I get "a round tuit," I will install DD-WRT into an old router so I can use it in bridge mode from the second floor to the first floor.
 

zandor

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I'd just kind of assume a UPS would screw up a powerline adapter. A lot of them go AC->DC->AC. Power strip I'm not so sure about. Then again anything you put in the way would likely cause signal degradation. I've never tried either. I did have a MOCA link (ethernet over coaxial) running for a while, but never any powerline adapters. Back in the day I used to just string cat5e around, then mostly switched to WiFi for stuff that was away from my desk, then bought a place and pulled cable and put in keystone jacks. :D
 
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