Not sure if those routers work differently, but you can't use your local IP (192...) for connecting. You must use your Internet IP (75...). Those programs that use Internet connection do no use local IP for anything. That might be the reason. But again, not sure.
I sorted it all out.
I had to go into the modem and set use public IP address.
The Planet M.U.L.E. development team has done quite a job.
This part
Finally I went to the Control Panel/Windows Firewall - Advanced tab
then highlighted Local Area Connection and clicked on the "Settings" button to
access the "Advanced Settings" window's "Services" tab.
I then added two new services MULETCP & MULEUDP at 192.168.0.100 .
both using external port 6260 & internal port 6260. I also tried changing the internal port to 6261.
was unnecessary.