Are u on wireless or lan connection?

There are several possibilities you can consider.:

1. If you're using wireless, consider changing the wifi channel. It can be channel interference, especially at night when your neighbours switch on their wifi.

2. If you are using wireless, try changing your password, it is possible that someone else got your pasword and using your network at night.

3. Make sure your internet adapter is obtaining ip address and dns automatically.

4. If your Internet adapter ia already obtaining ip address and dns automatically, you can try to set manual dns onto your router, eg google dns.

5. If none of above solve your problem, try switching router. Sometimes maxis stock router is giving slow response.