Online percentage going down

Your node was not available for satellites.
I would like to suggest to setup a port monitoring: How do I check my node when I'm away from my machine? - Storj Docs

If you want to know, when your node was not available, you can use these scripts:

Regarding how to fix - check your router (for example - reboot it at first), if offline events disappear or reduce - then you know what to blame.
If it’s not - then it perhaps your ISP. You can be sure only after setup of port monitoring.

Regarding satellites you can see the status there: