Longtime lurker. I created an account to reply here.
I was facing constant disconnect issues after the latest firmware update from gl-inet.
After downloading the modem version mentioned here, and upgrading the modem firmware through SSH to the router (P.S I used scp to copy the downloaded zip file from my machine to the router),
Using the latest modem firmware fixed all disconnect issues that I’ve been having on my Spitz!
I also turned off network acceleration and turned off Multi-wan cellular ping health check and that seemed to impact reliability as well.
Cheers!