Just an update to my ongoing problem getting my phone lines to work once consistently once I moved my Obi202 after my router.
Well, good news, I think I have the problem solved! Thought I'd try a new ethernet cable to connect the Obi and router to, and for good measure, I also used a different LAN port on the router. Now everything has worked great for about 3 days. Thanks for everyone's help and assistance on that and assuring me it should work with the Obi behind the router.
However, I do have a new minor problem now. When I'm on a call, it knocks out my internet connection on my PC that is also connected via ethernet to the router. (It doesn't impact other devices that are connected via wifi.) As a reminder, I have the Asus TM-AC1900 router, with stock firmware. The only change I made to the router settings was to set it so the Obi has an assigned IP address, as suggested earlier in this thread. Any suggestions on what other router settings I can tweak to fix this new problem?