Having still not found any solutions even from my host as well as from xenforo, I am therefore taking the liberty of reviving the subject in order to obtain help. Thank you.
You are going to need to provide more information.
Can you get into it and then your session ends and you're logged out immediately?
What's your server environment? Web server, relevant applications (php-fpm, redis, etc)
When did this start occurring and what changes were made to the server immediately prior?
Does this happen with everyone with admin panel access or just you? If there are no other admins then someone can provide database queries to manually make someone else an admin for debug reasons.
Are you accessing multiple XF installations? I have it when browsing between test/live. Perhaps it's even when accessing any other forum with the same cookie names?
When I connect to the panel there is not really a specific time before disconnection. I navigate the panel and arrive after 10 seconds. I reconnect and it happens over and over again.
I don't have the impression that this happened after modifications, I uninstalled the last addon that I had installed and the problem is still there. I would say it started a month ago.
Does this happen with everyone with admin panel access or just you? If there are no other admins then someone can provide database queries to manually make someone else an admin for debug reasons.
Are you accessing multiple XF installations? I have it when browsing between test/live. Perhaps it's even when accessing any other forum with the same cookie names?
I am currently only on this site. But it's a copy of an old forum of mine. But I don't think it comes from that because everything worked well at the start.