Calling for Michael is a bit like calling for Superman, he’s off making the World safe for Linux so the community tries to answer things before he gets back. 
Very strange you’re getting random outcomes, NSES-UHX didn’t come up with anything but for F7355 there’s some advice to clear your cache…
“Clear your Firefox (version 52 or higher only) caches by going to Preferences, Advanced, Network tab, and click the Clear Now buttons, shown below…”
12.04 - Netflix error code F7355-1204 and F7363-1260 - Ask Ubuntu
There’s more suggestings in the comments, i’m afraid I haven’t had this issue myself.
You could also try Chrome or Chromium if only to see if they share the problem.