Can't connect to Xbox Live through the Xbox 360 Dashboard in Backwards Compatibility games.

Hello.

I'm having a serious problem with Backwards Compatibility titles on the Xbox One, not being able to connect to Xbox Live even though my Xbox One is connected without any issue.

At first, while I had my profile downloaded on the X360 dashboard (albeit showing fewer Gamerscore points than I actually have in my same Xbox One profile), it would try to connect to xbox live but without sucess, showing the "8015190A" error code and suggesting
me to Test Connection.

By clicking on Test Connection it would take me to my Xbox One Network Settings page, where everything was fine (Wired - IPv4 and IPv6 - NAT Type: Open - No problems with Xbox Live).

Later, by trying out a possible fix - deleting my profile in the X360 dashboard by pressing START + BACK at the same time, then "Storage Management" and "Profiles" - I successfully managed to delete my profile from the X360 Dashboard; but since my "virtual"
Xbox 360 just doesn't connect to Xbox Live I can't even download my profile again and am left with no profile to play Backwards title games with.

I've already tried out every single troubleshooting/possible solutions I found, to no avail:

-Restarting Modem and Console;

-Clearing local Xbox 360 storage through the Xbox One settings menu;

-Changing MAC Address;

-Changing alternate port selection;

-Unplugging Ethernet cable and trying it out through a Wireless connection to my modem;

-Changing console region;

-Changing profiles;

-Reinstalling games twice and thrice, and trying out different backwards titles;

-(Lastly) performing a factory reset.

If possible, I'd also really appreaciate if every single one to reply to this thread could also test this out with any Backwards title you may have already installed and check if you can or cannot connect to xbox live through the X360 Dashboard. I don't
believe it's a problem on my end, but I'd only be sure if more people are also having this problem.

Thanks.

:)