Connection problems, by web or client [SOLVED]

I’m new with Nextcloud but not with Linux.
I run an install of Nextcloud 13.0.6 on a Raspberry-pi 3B+.
Everything went fine till today morning.
I’ve got trouble to acces my Nextcloud even via browser or client (linux and android).
On the browser the identification process take way too long and sometimes stopped with a wrong password error, or sometime pass through but long time. With client (Fedora, Debian or Android) the client stop looking for a connection with an ‘Operation Cancelled’ error message.
I’m sure abour my connection id and password. I can access to the server with ssh.
Thanks for your help.

Could be this app:

(there should be plenty of topics about that)

Yes it’s seems to be the solution. I found that the problem was around ‘bruteforce’, so I tried to change in confg.ini the bruteforce parameter from true to false, and it works fine. Bur it’s not a long term solution. I will dig the link you give me. May be I will need some help to setup the ‘bruteforce app’. Thanks for your reply.

The app solved the problem. Thank you.