Error -9836 and -50

I have that error popping up for around 2 weeks in iTunes 11.4 on Mavericks. The former is raised when I try to update Genius, the latter when I try to sign in which always fails in 11.4 but, strangely enough, works in iTunes 10 on Lion.

Error 9836 is, most likely, a side effect of Apple changing some connection protocols, that rendered some functions related to iTunes Store (notably, Genius and previewing songs) non-workable. As for songs reviews in iTunes 10 on Lion, I'm still able to make purchases, sign out/in, play audio/video podcasts, but when I click on "Preview" I see a loading dialog flashing up, followed by the standard player controls bar, however the track doesn't start playing.

I think this is true, because some people managed to install iTunes 10 on most recent macOS (as new as Mojave) and there they don't have these errors which proves that it's something system-wide and not iTunes-specific. This is further, albeit, indirectly, corroborated by the fact that on High Sierra I don't have such connection errors and everything in iTunes 12.8.2 works as expected.

I'm afraid they put it on their "Not a regression" list of minor, non-affecting issues, which means the troubleshooting of this problem on their part is put on hold indefinitely.