------- provisionally SOLVED!!! I think -------
This is WORKING FOR ME right now
sudo git init
sudo git config http.postBuffer 524288000
After multiples tryings of loading the repo and restarting the Supervisor and reloading it, sometimes i got error codes about github error connections. After searching and trying a lot, It seems that the repo size is too big and can’t end the operations before closing connection. So you should change some Git parametres.
(Yesterday i tried some other postbuffers parametres but it appears they werent large enough. Maybe in the future the same thing happends again 
)
–edited-- (added ‘fix’)
NOT a DNS problem.
I’ll explain you why… Because it can retrieve and load (and install/use) the HA Community Add-ons repository without a problem.
(Inside Github and similar url )