Mods are a common cause of "Online Fix" needs due to version mismatches or data processing lag.
Fully restart both your computer and your router to clear any temporary network glitches. don 39-t starve together online fix
If you're using a VPN or proxy server, disable them temporarily to see if they are interfering with Klei's servers. 3. Mod-Related Connection Fixes Mods are a common cause of "Online Fix"