I need help with RT-AC86U issues I am having now!

Hello, SNB Community.

I am looking for help,
I have a RT-AC86U with latest RMerlin Stable Firmware.

Issue is my WiFi is dropping and my connection is not very stable.
I was looking into was I could configure my address pool, so changing from 192.168.1.1 to 192.168.500.1. This was the start in a issue when I done this where you can change it on the page where the subnet is on the lan page.

I could not load into my router at all, so after two reboots, still the same issue.

Now I held...

I need help with RT-AC86U issues I am having now!