How to open up port on windows to be accessible from WSL2

[sboden]

I'm trying to get PHPStorm on Windows working with xdebug running on my WSL2 Ubuntu-20.04, I'm running Windows 10 pro.

I tried lots of things, among others this #4150 (comment) but nothing seems to work.

When I run ipconfig in a windows cmd I get this as local IP address of windows and WSL:

Ethernet adapter vEthernet (WSL):
   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::e5da:177a:4bfd:86a2%63
   IPv4 Address. . . . . . . . . . . : 192.168.50.1
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . :

Ethernet adapter Ethernet 2:

   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::b4d1:760f:7335:33b3%5
   IPv4 Address. . . . . . . . . . . : 192.168.100.39
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.100.1

When I check the IP address of WSL2 using windows powershell as follows:

PS C:\Software> $remoteip = wsl.exe /bin/bash -c "ip addr show eth0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}'"
PS C:\Software> echo $remoteip
192.168.50.2

All Windows firewalls are switched off. I also disabled ufw on Ubuntu.

In WSL2 I installed nmap to check open ports. These are the outputs:

$ nmap 192.168.50.2
Starting Nmap 7.80 ( https://nmap.org ) at 2022-02-12 00:00 CET
Nmap scan report for 192.168.50.2
Host is up (0.000065s latency).
Not shown: 998 closed ports
PORT    STATE SERVICE
80/tcp  open  http
443/tcp open  https

Nmap done: 1 IP address (1 host up) scanned in 0.06 seconds
$ nmap 192.168.50.1
Starting Nmap 7.80 ( https://nmap.org ) at 2022-02-12 00:01 CET
Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn
Nmap done: 1 IP address (0 hosts up) scanned in 3.03 seconds

$ nmap 192.168.100.39
Starting Nmap 7.80 ( https://nmap.org ) at 2022-02-12 00:05 CET
Note: Host seems down. If it is really up, but blocking our ping probes, try -Pn
Nmap done: 1 IP address (0 hosts up) scanned in 3.03 seconds

$ nmap 192.168.100.1
Starting Nmap 7.80 ( https://nmap.org ) at 2022-02-12 00:05 CET
Nmap scan report for 192.168.100.1
Host is up (0.38s latency).
Not shown: 995 closed ports
PORT      STATE SERVICE
22/tcp    open  ssh
53/tcp    open  domain
80/tcp    open  http
443/tcp   open  https
10001/tcp open  scp-config

Nmap done: 1 IP address (1 host up) scanned in 1.15 seconds

The WSL IP address from Windows doesn't scan, the WSL IP address found in WSL scans. Scanning 192.168.100.39 doesn't work, the 192.168.100.1 does (I guess that's my actual router).

I started "listening to PHP debug connections" on PHPStorm in Windows, which doesn't complain. And when I do check as follows:

netstat -a -n -o | find "9003"
  TCP    0.0.0.0:9003           0.0.0.0:0              LISTENING       10308

When I stop listening the entry also disappears.

I would like to open up port 9003 on Windows (where PHPStorm is listening) to the xdebug session running in WSL. Right now I get a timeout in xdebug while connecting (either to the IP address xdebug figures out, or any of the IP addresses above with xdebug.client_host and xdebug.client_port).

What do I have to open Windows port 9003 to my WSL2?

Regards,
Sven