My workaround for this problem was just to reset the nat table anytime I noticed that it had been emptied, and this solution worked quite well at keeping the Internet up.
However, I've decided to just forgo the whole issue altogether, and I installed an OPNsense router on my network to replace...
Yes, I did a factory reset (holding down WPS button while connecting power, then holding down power button). I also selected Factory Reset from the Admin UI. I can confirm that I had to reconfigure the router from scratch once it was accessible again. I enabled as few things as possible after...
I am not sure what the lease time is given by Fidium Fiber in my area. The <IP> mentioned above is my public IP on the Internet, not any local subnet. Although it does say 300 seconds in the renew, I only see this message once, at most twice in a day. Also, I don't believe the modem is rebooting...
I have an ASUS ZenWiFi BQ16 Pro (x2) with firmware updated to 3.0.0.6.102_36998 on both the router and node.
I've noticed a very strange, consistent behavior that started about two weeks ago, which I'm trying to debug. What happens is that, once a day, I see the following message in my system...