Sure I could try that, but
1. I have 1 (one) active working connection to a node; connected through port 8333,
2. I had the router from the beginning and in over 6 weeks it never gave me problems, constantly getting 20-30 connections,
3. I use the built-in uPnP feature which always has worked flawless as a port-forwarding tool.
So this tells me the port is not the issue here, right?