RAX30 Corrupted by Quad9 Setup Attempt

I made the mistake of trying to set up my router to use Quad9.

It took the ipv4 IP settings, but said the ipv6 addresses were invalid. I should have stopped at that point, but I didn't.

Now I cannot access the router at all.

If I use the router's IP address, the connection tries but finally times out.

(This is with FireFox and Google search engine. If I try other browser/search combinations, I get the Netgear irrelevant Web page. even with the router's IP address.)

If I use 'routerlogin.net', some Web page on Netgear opens that has nothing to do with the router.

I can connect to some places - I'm here, after all.

But other Web sites that I regularly access won't open.

I can't access my email.

Norton Password Manager won't open.

A hard reset of the router didn't help.

I'm passed the 90 days, so I can't access Netgear support. (Note: If I have to buy a new router, I will look for a brand that has better customer support.)

Any ideas? Or am I buying a new router?