I had myself problems with port forwarding in Proximus Router,
You do not have to go to Toegangscontrole but you have to click on your computer you are using example IMacvanAdam2
than Poortmapping(Port Forwarding) than add a new PoortMap.
Extern Start&Einde=25565 OR YOUR PORT THAT IS IN YOUR SERVER PROPERTIES
Poort=25565 OR SERVER PROPRETIES
Interne Host=Ipv4 adress UNLESS ITS AUTOMATICLLY