Technicolor TG582n and port 443

[#1]

For anyone else who has had a problem opening port 443 on their TG582n...
I needed to forward port 443 to a machine (mailserver) on my network. I'm using a Technicolor TG582n router. Recently I updated the firmware to version 10.2.5.2.FO.
I discovered that port 443 is set to direct to the admin screen of the router, presumably for remote assistance or something.
Simple, I thought, I'll just change that in the Game and Application Sharing settings.
Set up the port as a game/application and called it HTTPS. Then I tried to direct it to the internal machine.
I get the following error: "The port configuration of the game or application conflicts with an already assigned game & application. Assigning this game or application is not possible."
But in the list of games and applications there is nothing there that I have configured on port 443, other than the HTTPS port I had created.
So I go Googling about and see that some people have suggested PuTTYing into the router to issue several commands. Specifically: "service system ifdelete name=HTTPs group=wan"
Gave that a go and the router simply says "Failed to delete interface group from HTTPs service access list."
Remote assistance is allegedly turned off according to the router's web GUI.
Tried one last thing - out of desperation - I turned off UPnP and bingo, I was able to allocate port 443 to a different machine.

[#2]

I also get this error when I forward port 21 (ftp server)
"The port configuration of the game or application conflicts with an already assigned game & application. Assigning this game or application is not possible."

[#3]

You will need to unbind the inbuilt ftp server first , see here http://npr.me.uk/telnet.html#ftp

[#4]

@Damian,
Welcome to the PN forums.  PN's staff - Digital Care Team (DCT) - are inky around here during normal office hours.  At other times just other customers are available to offer help.
Are you trying to create a new Game or Application Name (GAN) in reference to port 21?  If you are, then that might be your problem.  Port 21 is already defined as "FTP Server".
The other possibility is that this GAN has already been assigned to a local IP.
A bit more detail of exactly what you've got and what is going wrong would be useful.

[#5]

Just to confirm what Hambo said about turning off UPnP to clear TG582 port conflict errors, when assigning a "game or application".
I got this error when trying to open port 80 by selecting  HTTP Server(World Wide Web).
Use UPnP was on, so I turned it off, and found that I was able to open the port. I then turned UPnP back on.
I guess it is a bug in my tg5852n, software release B.C.M.O

[#6]

TG582N has a Busybox bug that causes Busybox to constantly reboot IF both these conditions are true:
1. There is a W8, W8.1 or W10 device connected to the network via WiFi
AND
2. UPnP is switched on.
See: https://woodygems.wordpress.com/2014/11/11/a-fix-for-wifi-andor-lync-drop-outs-in-windows-8-1-and-wi... and read the bottom half that starts "Applications dropping out (particularly Lync) when connected to a WiFi network"

[#7]

Have you confirmed that yourself? I'd be surprised if UPnP on a Technicolor router has anything at all to do with the busybox shell.

[#8]

Yes, that turning off UPnP increases stability - particularly for Lync/Skype/Skype for Business calls - on the routers affected.
No, I don't know if UPnP crashes busybox - I only read that blog entry and if you look at the clues, the author probably knows what he is talking about.