PPPoE keeps disconnecting

Hello, I’m using an AC1300 Version: 3.211 and my WAN provider is providing me with a PPPoE connection. The issue I’m having is that it keeps disconnecting and reconnecting, and I think I’ve narrowed it down to keepalive?
For testing purposes, I connected a LinkSys device, which appears to be working fine and I am not experiencing any disconnect issues. I discovered a keepalive setting of 25 seconds on the Linksys PPPoE configurations.
My question is, where can I change the keepalive timeout settings?

My WAN provider just provides a PPPoE username/ password, no VLANs etc.

There should be settings in LuCI → Network → Interfaces → WAN → Edit → Advanced Settings

I do not work for and I am not directly associated with GL.iNet

Can you clone your LinkSys’s mac address to the router and check?