There is currently a problem with the Object Storage from OVH that is used to serve media files for Masto.host and this is affecting both loading uploading of media.
They are already working on it: http://travaux.ovh.net/?do=details&id=47465&
Sorry about this. Hopefully they fix the issue soon. I will post here when I know more.
The root cause of the problem is still not solved but for the past 5 minutes it has been working without a problem, slower but coming back.
I will keep monitoring the situation and update it here.
i love how these things happen and then get fixed faster than i can realise there is even something wrong 😄
@Nikolai_Kingsley Glad you didn't notice :)
This one was really strange because it failed randomly but it was some issue on OVH internal network, nothing I could really control.
Server run by the main developers of the project 
It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!
Just to confirm that the issue is fully fixed and everything has been back to normal for the past 3 hours.
Please let me know if you notice any problem.
Sorry for the inconvenience.