Thank you for the detailed information. May I ask if this also happens in your smartphone?
Also, please disable killer WIFI smart features.
Device Manager - Network adapters - Killer Wi-Fi -Properties
Power: Uncheck Allow computer to turn off this device
Advanced:
Killer Prioritization Engine - Disabled
Roaming Aggressiveness - Lowest
Preferred Band - Prefer 5 GHz
Transmit Power - Highest
Then, please restart.
If issues still persist, please Uninstall Killer Control Center.
Settings - Apps - Installed apps
Uninstall Killer Control Center / Killer Performance Suite
Reboot.
If you're also having issues on your phone, it's possible that it's a modem/ISP issue.
Please let me know how it goes.