I have a Logitech G710+ now and that is my first mechanical. I believe I paid 70 for it which IMO already feels like a lot to me for a keyboard (I know mechanical can go for a lot more). If it's good enough I may need to get 2! I like that it has the numpad too.
This should explain how to set it up.
You need to have the default gateway set to the IP of the pfsense LAN IP or the IP to access the pfsense GUI. Like was said before, the modem and router should have a different IP.
WAN goes to the modem. What is the DHCP server you have running on? It may be something with that as well. You could verify that by using the pfsense DHCP server to see if it works first then re-enable the one you are using.
I actually have used pfsense for 10+ years now. I just don't use it...
What he said. Also you need the DHCP server set on the IP of the pfsense router for the default gateway. I think in Windows server it defaults to the IP of the server.
EDIT: What does it say if you try 192.168.1.50?