I did as you said and tried out wireshark. I tried it first with my chat app, and that worked ok. I received the expected data (in hex), and i then tried my other application, and received a warning called "Zero window".
I looked it up and found out that it means i'm sending too much data. The server runs very fast and is spamming the client with way too much data i believe is my problem. That means that the client will process very old data, especially when it runs at such low fps as 60 compared to the server running super fast.
Does this seem like the probable cause?
Thanks again
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Edit: I fixed it now so it works. I made the server only send a packet if it just received one from the player.