TF2 - Unable to join multiplayer after 1 or 2 games.

Hello.

I'm writing this new post because the only other one that relates to my problem has been marked as "Solved" and the resolution mentionned would be changing the GPU because the game would chose to use Intel HD Graphics instead of main GPU.

Well, that's not my case.

Problem description :

Whenever I want to play multiplayer, I can usually join without any problem. I can then play one or two games. The first time I could play 4 in a row. Then, I'm disconnected (I see "Connecting to server" with a counter on the left.) and I cannot play any more games.

If I go back to main menu, I cannot join multiplayer again. If, by chance, the connection seems to be established, I get a black screen for a looooong time, then "Connection timed out" and back to main menu.

What I tried :
I tried to change my DNS (Tried my Internet Access Provider DNS, Google's, Open DNS) to no avail.
I tried to install network monitoring softwares. To no avail. Even if TF2 is set on Highest priority.

Specs :

My computer is an AMD Ryzen 1700 (8 Cores, Hyperthreaded), 16 Gb of DDR4 3200 mHz, SSD, Asus GeForce GTX 1060 6GB STRIX Gamer. I joined my DxDiag.

Additionnal info :
I have absolutely NO PROBLEM with any other game (Mainly Warframe, Eve Online, but also Space Hulk Deathwing) when it comes to multiplayer.

The ONLY way I could play again was by restarting my router ! The ports are opened (else I couldn't play the first 2 games), I have a pretty decent connection for my location.

So, the problem seems to be linked to my IP address somewhat. And I can't figure out WHY !.

Please, tell me you have a solution.

Thanks,

Melgrin.