LB2120 Modem Needs rebooting every 15 hours

I just got one of these modems to use as a backup for my cable modem when it decides to go out. I got it working, in bridge mode and in line with my RBR50 Orbi router and everything seemed to be working....but after 15 hours up it appears to lose connectivity.

I say appears because when you check the status page it still says it has a connection to the cable modem, and even though no device can make a connection Out to the internet, I can still connect In to my network with a vpn I have setup. Which was lucky because then I could access the modem's configuration page and restart it and everything goes back to normal.

This has happened 3 times in a row, every time at the 14/15 hour mark. I've seen similar posts but they're all from people using the modem exclusively in for the cellular connection, not wired.

Needless to say having to manually reset the my backup internet connection because it kills my primary internet connection makes it worthless.

Anybody run into something like this?

Firmware says that it's up to date