USB WAN keeps disconnecting (AX89X)

[Qbcd]

I'm testing the USB WAN function on my AX89X with a Pixel 7 Pro phone and it keeps disconnecting every few minutes. Here is what the log looks like:

May 4 01:34:51 WAN Connection: WAN(0) link down.
May 4 01:35:12 WAN Connection: WAN was restored.
May 4 01:35:36 WAN Connection: WAN(0) link down.
May 4 01:35:57 WAN Connection: WAN was restored.
May 4 01:36:21 WAN Connection: WAN(0) link down.
May 4 01:36:43 WAN Connection: WAN was restored.
May 4 01:39:40 WAN Connection: WAN(0) link down.
May 4 01:40:00 WAN Connection: WAN was restored.
May 4 01:42:10 WAN Connection: WAN(0) link down.
May 4 01:42:30 WAN Connection: WAN was restored.
May 4 01:44:21 WAN Connection: WAN(0) link down.
May 4 01:44:43 WAN Connection: WAN was restored.
May 4 01:50:49 WAN Connection: WAN(0) link down.
May 4 01:51:10 WAN Connection: WAN was restored.
May 4 01:51:56 WAN Connection: WAN(0) link down.
May 4 01:52:17 WAN Connection: WAN was restored.

It always takes 20 seconds to reconnect, I guess because I have set the network detection interval to 20 seconds (ping to 1.1.1.1). Sometimes it gets stuck and you have to restart the router before it will reconnect.

On the phone side everything appears to be fine. I have a strong 5G signal and I have tested in the middle of a disconnect and the phone remains connected to the internet with good signal and USB tethering stays on (the phone still shows up in the router GUI while WAN is down). It would also be weird for my cell connection to drop every few minutes regularly like this, so I'm fairly certain it's the router. Any ideas for how to fix it?

Thanks.