If its using the pseudo bridging feature in openwrt (relayd0, try giving yourself a static in 192.168.8.1/24 and seeing if you can then reach 192.168.8.1

There is the nuclear option.
Do the same button pressing when powering up and reload the firmware.
Instructions at Debrick via Uboot - GL.iNet Docs

Given neither you and I quite know how its configured. You might be better with the latter anyway!

good luck
Simon

Simon