Supsites not loading - keeps reloading in circles

Hi There,

I'm having issues with the domain mapping (I think its the plugin) on my multisite. It makes all my subsites stuck in a loading loop.

When using Mozilla to open any subsites (with mapped domains) it keeps loading indefinitely. Subsites without domain mapping loads normal (slow, but normal).

The main website ( laods normal as well.

Any advice?