I normally don't use Firefox very often but wanted to give it a try again. My usual default browser would be Vivaldi (which is unfortunately Chrome based). Anyway I usually have turned on my NordVPN system wide (Windows 10 Edu V. 22H2), which works fine on Vivaldi. I turns out it does have a weird side effect on Firefox. The DNS resolution for "google.com" just doesn't work anymore. Any http request runs into a timeout. Strangely it works on any other google domain like google.de or google.org, also I couldn't find any other domain to reproduce this behavior. Now this wouldn't be such a big deal if google's reCaptcha wouldn't also be used by a lot of webpages and the api is hosted on google.com so basically the reCaptcha box just never appears and I'm stuck on those pages.
I tested it with v. 123.0 (64-bit), in private mode, in safe mode, FF portable 115.8.0 ESR and it is all the same strange behavior.
NordVPN also does have a FireFox Extension and using this extension everything works again.
Also tested it with the FF MacOS version and NordVPN client, here it works.
I can't really explain this behavior other than some weird Firefox behavior together with NordVPN or some interaction with the Windows 10 vpn layer.
Can someone confirm this behavior on Windows? I assume other VPN providers like Mozilla VPN don't have this?
[Update]: Forgive me it was late yesterday. I still can't explain the behavior exactly but for sure the reason is the split tunneling feature of NordVPN. I had it enabled as I only wanted certain apps to go through the VPN and Firefox wasn't on that list. So actually the NordVPN client should have treated FF routed through my default system connection and FF should just not have been routed through the VPN. Now it is more likely that it is some split tunneling bug that for whatever reason the google.com requests are treated differently by NordVPN/FF and are kind of blocked on my side or wrongly routed and never reach the google server.
[Update2]: As @LucidBoi@lemmy.world noted in the comments, the problem is not only related to Firefox and therefore wrong in this community. It actually also works on other browsers as well. It seems to be a problem of the windows NordVPN client and/or Windows 10. As soon as you use the split tunneling feature and exclude a browser from it, suddenly google.com doesn't work anymore. Very strange, but that's it. Actually for Firefox you should just use the NordVPN add-on anyway as it gives you a lot of flexibility to use split tunneling per domain, which actually works also for google.com then.