UDP needs to trigger UDP and TCP needs to trigger TCP.
thats why u still need 2 rules.
also, please reduce port range in both rules to 6112-6112 and "translate to..." to 6112
what is your complete set up of routers? like, what things do u have between your pc and the internet connection in the building (because u said u live in apartment building, could be that u are connecting to a 2nd router for the whole floor or something like that.)
so there is no device with a name which could be your computer? i guess u tried to test all devices already...