@thegamingmineblo which default famicom roms? Are you using a custom recalbox image?

I'm also testing the netplay functionality and i am not able to get it running. I have 2 PCs with Recalbox 18.06.27 (x86_64), both with identical settings and roms and connected to the internet.
When i start the host on the first PC and try to join from the second PC it always says:
"Failed to initialize netplay."

I tried with catsfc and snes9x (no snes9x_2010)
I scraped and hashed all my roms
And in Netplay Lobby i get the green Ok result (Rom and core match).
But still it does not work ("Failed to initialize netplay" on the PC that tries to join the host).

++UPDATE++
Problem solved! It was the UPnP-Settings in my Router. I activated UPnP and now it works :-)

@substring I have not tried/downloaded any n64 roms because of the spotty performance reviews, but I did see they had a special mapping for n64 on the x gaming website that was hyperlinked.

@dummello

Hi to you. Absolutely nothing understood. You have a game and it launches another games?

thank you. i am still a novice with that roms

xarcade works only in Recalbox 4.0.0 https://github.com/recalbox/recalbox-os/wiki/XArcade-configuration-(EN)