I have a Linux webserver in a local Hyper-V VM with xdebug enabled, which uses TCP port 9000 to connect to Eclipse on the Hyper-V host, for PHP debugging. The VM connects through a Hyper-v internal switch and I am sharing my host network with this switch. Thus, the VM connects from a unknown or public network.
I can only get a connection from the VM on port 9000 to the Hyper-V host, when the Windows firewall is disabled. I tried creating a firewall rule to allow this specific port, or one which allows all traffic, it didn't help. My firewall rules for Ping and SMB network shares work fine between these two for example.
This issue only occurs on my laptop and my PC using the same configuration works fine.