Question Slow Internet on Laptop but not others (Wifi/Ethernet the same) and can't connect to 5Ghz wifi anymore

[SumTing]

Ok, so I have MSI GP63 Leopard 8RF

Network Spec:
Wireless card : Intel(R) Wireless-AC 9560 160MHz
Ethernet : Killer E2400 Gigabit Ethernet Controller

I have been using this laptop for a year + now, mainly for gaming and never had any problem until last week I noticed my Down/Up speed is decreased by 70% as if it's capped at 10Mbps out of nowhere. Tweaked my laptop for pure gaming so never had anti virus, and always update all my drivers here and there. I thought it was my internet so I tried on my other laptop but the speed seems normal. I also don't think my laptop caps the down/up speed because when I'm downloading, my latency has a lot of RTO and browsing becomes really slow. Meaning I really only received only 10mbps speed.
Somethings I tried :

• flushdns
• reset network
• reset modem
• Use ethernet cable instead of wifi
• Updated BIOS
• reinstall driver
• "Reset This PC" where everything is cleaned/reset
• Changed some settings in Wireless Properties>Advanced

None of the above works, On top of that, I also can't connect to the 5ghz wifi anymore too, just stuck in connecting then failed to connect. All my other laptops can connect to all the wifis and have normal speed while this laptop is [CENSORED].
So I'm out of ideas. any suggestions?
Last resort is get new wireless card/usb for my laptop :/

TL;DR My Laptop suddenly has slow Internet on both Wifi/Ethernet and can't connect to 5ghz anymore while other devices are fine.

❌ No swearing on Tom's Forums please

 

[SumTing]

UPDATE : Did a clean install, can connect to 5ghz now but speed is still capped at 10mbps it seems like.