You need to understand how WiFi works and also that Internet providers do not guarantee WiFi and don't sell you WiFi.
Testing needs to be done using wired connections and depending on wireless networks in proximity to yours performance will vary.
For gaming WiFi is never recommended so would advise on find a way to not use it for gaming, either by connecting using Ethernet cabling or a Powerline adapter.
If I've helped let me know 🙂
10 year's managing 9 Virgin Media accounts, and things never got any better, closed last 4 accounts since January 2021 :L
I give 'my' experience to help where possible.