Friend's cannot connect to my server

Hey everyone,
Up to this point i’ve tried almost everything I could think of, portforwarding, firewall port opening, allowing teamspeak through the firewall, uninstalling reinstalling, rebooting my router.
My friends still cannot connect to the server, and I cannot think of anything else to try.
I am on a windows 10, my router is a TP-Link.
If anyone can help i’ll be grateful.