Error "Forbidden" "You don’t have permission to access this resource."

[nicolax]

CMS Version : 3.3.5 - A brand new installation.
Installation Method : Custom Install (Web Hosted - OVH.COM)
Operating System : Linux

Context
I just installed a brand new XIBO CMS on my personnal web cloud hosted by OVH.com.
Not any warning/error during installation.
xibo is placed in a sub-folder, and is reached through an alias (xibo.domain.com)

Issue
=> when I try to change any setting, or try to save something, an error appears " Forbidden - You don’t have permission to access this resource."

Could any one help me please?
Thank you

Kind regards,

[Vishal_Debipersad]

Since you are using linux, would it be better to use Docker? everything from Docker will run after first deployment. Also upgrading is better and easier.

[nicolax]

That would be great, but I have this constraint to use a Hosted (and mutualised) Web Server …