I was about to ask about it here.
The article above is from 2016. But traffic seems to be the problem (again), see here:
https://forum.fanart.tv/viewtopic.php?f=8&t=8471
"The assets server is being hammered, the certificate hasn't expired it's just the hosts killing the traffic when it goes too high and for some reason it's putting out weird errors.
I added some rate limiting yesterday which initially seemed to help, but weekends are always higher traffic anyway. I'll have a look at modifying the rate limiting."
I won't get any images right now from fanart.tv :-(
sorry, completely missed that this is an old post
thanks for posting the right source