Host a game with console commands

First client clicks a button with execute console command “open landscapemap?listen”
Second client clicks a button with “open 127.0.0.1” (tried with local and with internet ip)
Also i opened Port 7777 UDP

Nobody can join where is the problem?

Do you have Steam in use with Online Subsystem in your game? Turn off Steam on the computers. open mapname?listen and open ip should work then