Connection to the Server Not Fast Enough (but it is)

I have recently had numerous issues with videos stuttering and freezes and sometimes (especially on mobile client) get the message; the connection to the Server Not Fast Enough. I can run 4K movies without hiccup so doubt this is hardware related.
On both xbox, web and mobile client certain video files get these issues while from what I can tell more or less similar files in terms of resolution, format, container etc run just fine. The problem files run fine when played locally, e.g through VLC.
I've attached a table with info about 4 similar files, two play fine on all clients, two freezes after a few seconds.
I believe this problem is fairly new. the only change I have done lately is to upgrade line from 60 Mb to 100 Mb line and connect PC (Win 10), Xbox, TV with cable instead of wireless, mainly to be able to play 4K. I also attached logs. Can anyone see what the problem is ?