VMIX EXTERNAL SRT OUTPUT ISSUE

Hello everyone!
I need to use vMIX as a multi srt encoder to transmit videos to a remote location outside our studio.
I created 4 external output enabling srt as caller mode on my vMIX in the studio.
It works, on my local lan with VLC I can play all 4 streams using the IP of the windows workstation hosting vMix and the right SRT port.
I need to receive that streams outside my local lan, I have configured my firewall so that connections from outside on our public IP are correctly routed to the local ip of the windows machine with vMix to the right port but it is not working, anyone had the same problem? Is there any setting that I have to check on vMIX or in my windows pc ? Thank you!