Internet slows down to less then one MB with VPN running

Hey guys, I moved to a new apartment and when connecting to the apartments internet using a vpn, my internet speed drastically drops (from around 50-60mb to less then one mb or just close above one). I never had this problem with any other networks and using another network resolved this problem on my devices (it happens on all devices). I do not have my own internet provider, I use the one from my landlord and I connect via an TP link Router that is connected via Newtork cable to the wall, so I think this it is perhaps routed trough a „main router“ from my landlord with the other apartments. When I disconnect from my vpn my internet speed goes up again to the earlier names numbers. I am not sure if my landlord somehow can slow my internet if he detects an vpn, but is there a way to find this out? Or perhaps are there any problems on my side?

Another thing I found out is, that if I work from home and connect with my work vpn to the work servers, the internet is not slowed down and works as intended

Thank you so much, I will give it a shot right now

Okay it works, my internet is now back up to 45-50mb which is enough. Thank you again so much, but now I am wondering why my landlord would restrict the network in this way?