Hi,
I also have an OVH web hosting, and I encountered several problems such as blank pages and problems connecting to certain pages. I solved the problem by enabling the option CDN / HTTP / 2 on my mutu. I do not know if it can help you but I’m on Gravelines and it works even if some error still persists
Hello ffs69 and others,
As my OVH plan will expire in a few weeks and after some time analysing alternatives, I finally moved to LWS.fr (still a shared hosting, “starter” plan).
My Nextcloud works now fine, all GUI components are displayed correctly, gallery app works fine, updater works like a charm… Short story, all the problems I have had with OVH are now gone with LWS.
And furthermore, I noticed that the Nextcloud pages load faster now, it runs really smooth.
Bye bye OVH 
I can say more if you want some details…
Cheers
Hello all,
Same as @CFelten, just to tell you that I solved my problem by quitting OVH.
For my part, I turned to a host who works as a consumer cooperative (Ouvaton.coop), so I add ethics and cooperation in my financial and temporal expenses for web hosting, also in France.
Everything works very well! And the customer service is responsive, available and human.
Thank you to everyone and long life 