Hi benjprice19. Since your account works during weekdays but mainly fails on weekends, this is most likely related to higher local network traffic or a network connection issue rather than the account itself. Servers usually have much heavier traffic on weekends.
A few things you can try and see if this will improve things for you:
- Switch between Wi-Fi and mobile data
- Restart your router
- Disable any VPN or custom DNS apps
- Try logging in from another network
- Fully closing FC Mobile
- Clearing the cache (if you're on Android)
- Logging out and back into Google Play Games or Apple Game Centre
- Reinstalling the game, but only if your account was linked to save your progress
Testing another device may also help confirm the cause of the issue.