TLDR – It was an IP conflict between the modem in bridge mode and the USG Pro who both wanted to use 192.168.1.1Hello y’all!
For several years now I have been battling this problem and I have finally found a solution to it. So I thought I wold share what I have come to find was causing the problem and how I resolved it.
Please don’t judge me on how long it took to work this out. I feel quite the fool now already!
So, to the point. I have a Unifi USG Pro running my network (2 unifi wireless APs, several network vlans, firewall, all the normal home lab kinda stuff)
The USG is plugged into the supplied NBN(I am in Australia) modem which is set to bridge mode and the USG does the PPPoE stuff.
This all worked well for over a yer but then one day started to drop the internet for about 5 mind every hour or so. I bought a new ‘stock’ modem and replaced that, I used the stock modem to do the PPPoE stuff (which should have fixed the problem) and I finally removed the USG completely.
I still had the internet dropping out every few days for a little bit but I put that down to a bad connection.
This is how I have had my internet for the past few months, no vlans, no advance firewall, “The worst!”.
A week or so ago I setup a HP EliteDesk 800 G2 mini with PFSENSE and connected it up as the main router with my stock modem back in bridge mode again. And almost right away I started seeing warnings in the logs about an IP conflict. Further investigation showed me that even though the bridged modem was on the WAN port it was still causing a conflict with the USG.
Solution, I set the USG Pro to use 192.168.1.254
A simple solution to an annoying problem but all my googling to find a solution never lead me down this path so hopefully someone finds this and it can help them too. I almost sold my USG!!!