Running eMule in Windows Sandbox Firewall Problem.

I have never used Sandbox before so it is a learning curve for me.

I can run eMule v0.60c-Installer64 in normal Windows. (the old eMule program has been updated recently by a dedicated programer).

In normal Windows, during instalation, I allow the eMule program in the popup Firewall box. Private network is ticked and Public is not ticked, by default.
I then tick "use UpnP to Setup Ports" in eMules setup and Windows Defender Firewall does it's magic and says "UPnP successfully setup forwarding for ports 63898 (TCP) and 38908 (UDP)".

Then I click on the Test Ports button and the browser opens up and gives me 2 green ticks (TCP & UDP).
I also create an inbound and outbound rule in the Windows firewall, allowing connections. (every little bit helps).

eMule then runs fine and is seen on all of the eMule network.

But, installing eMule into the Windows Sandbox is a different story.
During instalation, I allow the eMule program in the popup Firewall box. Private network is NOT ticked and Public is TICKED, by default. I changed that around.

I then tick "use UpnP to Setup Ports" in eMules setup and Windows Defender Firewall does it's magic but says "UPnP failed to setup port forwarding, please forward these ports if necessary."

Then I click on the Test Ports button and the browser opens up and gives me a red cross, saying:
"TCP connection test failed.It was not possible, to establish a TCP connection to your eMule.Other users will only be able to connect to you with the help of a server, resulting in a low ID for you. While eMule still works, this will give you several disadvantages. Therfore it is highly recommended to solve this problem."

I also create an inbound and outbound rule in the Windows firewall, allowing connections for eMule. Makes no difference. I then turned off Windows Defender Firewall. Made no difference.

I closed Sandbox which deleted everything. I opened Sandbox again, turned off Windows Defender Firewall & installed eMule. Made no difference, still get the "TCP connection test failed. It was not possible, to establish a TCP connection to your eMule."

With the firewall on or off, emule will connect to eD2K and Kad networks but the files showing from a search is small.
I need to get it connected properly.

Seeing that TCP will not connect with the firewall on or off, that leads me to think that the problem is not with the firewall, Possibly something to do with sandbox settings and the way it talks to my router. I have never "forwarded ports" before. Do not know how to do that but willing to try. My modem/router is the Netcomm NF18ACV.

I would appreciate any suggestions.

- - - Updated - - -

An update: I turned off the Firewall in both the Sandbox and normal Windows, thinking that one of the Firewalls was the culprit in not alowing the TCP connection. It made no difference.

So, ignore that the program happens to be eMule, what is the reason for the blockage of the TCP?

I will post this problem in the eMule program forum. Official eMule-Board

Update on 28/10/2021.

Upgraded to Windows 11 Pro.
The problem still remains.

Moving on.....

Update on 06/11/2021.

Thought I would activate the built-in Virtual Machine & try that.
As I have never done that before, I enjoyed the new experience.

Alas, the TCP connection test failed. UPnP failed to setup port forwarding. That was with me allowing inbound & outbound connections in the Firewall, for eMule.

Disabled the Firewalls in the VM & the default install of Windows.
No change. TCP is still blocked.

Uninstalled the VM & disabled it & the Sandbox.

The technical fix for this is way above my knowledge.
I am just posting this for those who may wish to use eMule in these configurations, so they will not waste their time.