Hello, Community!
This post addresses an HG531 V1 router problem. Please see more information displayed below.

ISSUE DESCRIPTION
I have an HG531 V1 router given to me by my internet service provider, but they modified the firmware to make it impossible to change anything.
I only have acces to the settings shown in the below images:


How can I access the complete router panel? And how can I change the firmware?
Please assist me in this HG531 V1 router problem. Thanks!