I was using an old release of OpenWRT (19?) for a long time on a Linksys WRT3200. I bought a second unit, used, so I could slowly and carefully get 23.05.3 configured before switching. The 23.05.3 system would run for a while, then I would need to power cycle the cable modem to get an IP from Comcast The old release would run for weeks no problems, the 23.05.3 would only run for a few hours. Then my cable modem just died (no lights even) so I bought a new Nighthawk. I just could not get it to give me an IP on 23.05.3. Plug my laptop directly into the modem; it worked great. It is just OpenWRT that can't get an IP. Go back to 19.* and it works.
So, I gave up on my modem and rented a Comcast xFi modem/router. It worked. So I upgraded the original Linksys router and now both are running 23.05.5. Both on 23.05.5 with the xFi doing an extra roter layer between.
However, I decided to put the Comcast modem/router in bridge mode (ie, turn off their router). After this, neither OpenWRT router can get an IP from Comcast. I switched back to useless-double-router mode and they both work. Does anyone have any ideas? Having their router between prevents IPv6 from assigning addresses.
BTW: I tried 24.10.0, just in case that would fix something. No dice. The router won't boot. I reverted to the alternative image and got it back. I think I will wait on that release.