RBR50: Can't change DNS settings (error msg that existing log-in can't contain non english words)

Hi - I think we're missing each other on this -- 

In addition to "routing" I'm using the orbi to do Vlan taggng and handle the credentials necesarry to log into my fiber connection. That is the login information I populated when I set up the Orbi and it's been working fine. Something changed at some point (firmware update?) because, like I said, I put that info in to the Orbi in the first place so I could connect to my fiber. It didn't generate the error then. Those credentials are required for my Internet won't work. But with those credentials there, I'm unable to "save" (or even "test") that page. 

So while I realize what I should do to change the DNS settings IF the Orbi was working properly and not generating the "invalid log-in/non-english words" error, my point is that I can't do that (or anything) on that page because that page also contains (and must contain) my ISP login information, and that log-in info is apparently what's now generating the error. What changed? I don't know.

I'm pretty that removing my ISP credentials would allow me to adjust the DNS settings (or whatever else I wanted to do on this page) and save the changes, but that would be pointless because the Orbi would no longer be able to communicate with my Fiber ONT and I'd lose my Internet.

Is there any way ot report a bug to Netgear without paying for extended support?