I'm on 4.10.4 and am now having trouble playing NESN content. I went to reauthenticate, and it gave me a link like https://tv.nesn.com/123abc — I click that and it redirects to watch.nesn.com, but the token doesn't seem to ever finish coming through.
If it helps to frame this, I'm not sure that those tv.nesn.com links are the "right" way anymore (though I could be wrong). Doing it on my Apple TV I had to type in my email address and get a code to authenticate.
Happy to help test and/or provide any necessary info.
Edit: now I'm seeing the posts from a week ago. Clearly I missed those in the flurry of everything else. Ugh. Still...if there's anything I can do to assist, happy to test/help.