Online score just drop down…how to get 100% again?

You can also use the search: Search results for 'Your node is still considered to be online but encountered an error status:solved' - Storj Community Forum (official)

Please, search for error “Ping satellite failed” in the storagenode’s logs to find can satellites contact your node.

This is warning, not a error. So severity is lower. The UDP port forwarding is not mandatory yet, but highly recommended.