Plex - Access But No Access

Hey guys,

Been trying to google this issue and been asking my friends, but got no result :S
I use(d) Plex on mobile (great way to kill time while waiting for the train...) , on my Xbox 360 as well as laptop / PC. I have access to at least 2 servers, but I cannot access any server.
Plex loads as it should, it is updated to the ltaest version...but it leaves me out in the dark, stating the servers are offline. Odd thing is, I *can* access the erver when I take the laptop to my friend and log on to Plex using their network, but as soon as I get home it's all dark again.

I did receive a new modem couple weeks ago, however the problem started way before that (few months now). Laptop is Win10 on a HP255 G3 (hey, it works ), PC is Win10 but is taken offline by me (just for backups and offline games), Xbox 360 is just that. Haven't installed Plex on my new mobile yet, as I cannot access servers I haven't bothered - yet.

Any suggestions, as to what I can try to get it running? Would love to watch my fav series again
Thank you in advance

 

OR a suitable, working alternative is welcome, too.
Seems I ran into a problem that is apparently a real problem XD

 

Thank you, plodr!
I tried searching everywhere except Narnia and couldn't find a solution. Either I missed it, or I looked in the wrong places.
Long story short: Got it sorted thus far, thank you I can go back to binging old series again *happy dance*