Can jmd help me with my problem?

For about 2 months I have ping problems in Fortnite, ONLY in Fortnite. I can't play it anymore and I do not know how to fix it. I have already written to the support, but they mean I should change the server or restart my router (I've already tried restarting it.

Can I fix this somehow?

You are the only person who can help you. We do not know any stats. Neither about your pv, nor provider, nor router, nor settings of the router etc etc etc. Even the support (if it's a good one, no idea how that is with Fortnite) lets you first make a network test, so they look over it can and can judge.

In short: I'm sorry, but here you will be able to help with the wealth of information you give, no one.