"Cannot load app" error when loading ClojureVerse (especially from existing tab?!)

Sometimes when trying to go to ClojureVerse, I get the following error:

Cannot load app

It looks like you are offline! Please check your network connection and try again.

It happens repeatedly on different wifi networks that all work fine for other sites.

It seems to happen more frequently, almost reliably, when trying to go to ClojureVerse in a tab already on an existing page like GMail.

It started to happen, to the best of my recollection, sometime in mid-January.

I saw that warning several times too, thought it was a problem of my network or sites was down for maintain.