Question Strange ping issue, anyone know the cause/fix?

Apr 8, 2020
Warning: Wall of text incoming.

I have decided to see if anyone here can help as I have exhausted every possible fix I can think of and can't seem to find any other solution to this strange issue.

Here is what happens:
  • Join Rainbow Six Siege game, my ping is ~35, fluctuates up or down ~5 quite often
  • Alt-tab out of game, wait a few seconds
  • Alt-tab back in game, ping is at stable 9 for a few seconds, then shoots back up to ~35
While alt-tabbed out of game I have asked a friend to tell me what my ping is on the scoreboard and he has confirmed that it stay at a stable 9 ping while I am not tabbed into the game. Does anyone have any idea what causes this? Is this normal (I'm pretty tech savvy but not when it comes to networking)?

Troubleshooting I've tried:
  • Contacted ISP with tracert info (they said the routing seems normal)
  • Reinstalled Win 10 Pro ver. 1909 (even tried a self-made stripped down iso)
  • Tried various BIOS versions and settings
  • Updated all relevant hardware drivers
  • Tried dozens of different Win 10 settings
  • Tried several different Intel LAN drivers
  • Tried various Intel Adapter settings
  • Swapped out Cat6 cable
  • And many other things that aren't coming to mind right now
My setup:
Asus Rog Strix B450-F Gaming
Ryzen 2700x
Corsair Vengeance LPX 2x8GB 3000MHz
EVGA GTX 1070 SC Gaming

P.S. I live in an apartment complex which provides 100 up/down through Boingo. I used to get consistent 9 ping some time ago but don't recall when this started happening.