I set the protocol to Both. Still not sure that was necessary.
Details on exactly how I got it all working are here:
Though the process is still somewhat ongoing.
Surprisingly, I’ve had my computer shut down for two days, partly due to being busy with some house renovations and partly just to see what would happen, well, on rebooting, got a connection and YaCy is still working in sever mode, though still on the same DHCP assigned IP.
Perhaps the lease time is very long, or it’s just coincidence I was assigned the same IP or the router is “smart” enough to recognize the machine.
Additional specific info might help, like what model or brand router? Did you set up the local IP or is it DHCP assigned? A screenshot of your router settings perhaps? Your operating system?
I did come across a setting for UPnP in YaCy. It was turned on by default but had a failure to connect error. I unchecked that as I was not using it. My router also supports UPnP but it was turned off.
If it had been turned on in my router, perhaps YaCy would have connected automatically, however, from what I’ve been researching, UPnP may not be as secure as direct Port Forwarding.