I get the same on firefox with ublock origin, but it works if I turn off ublock or use chrome.
on my android firefox, I can't load any google properties - it just redirects to a help page about how to clear my cache (clearing the cache doesn't help)
on my android firefox, I can't load any google properties - it just redirects to a help page about how to clear my cache (clearing the cache doesn't help)
So yes, maybe the servers handling google groups are a little too busy.