Nextcloud desktop client "access forbidden by server"

I have installed nextcloud on some shared host but sometimes find this problem, all is fine but when login in windows desktop client always error, it appears “Access Forbidden by server. To verify that you proper access, click here to access the service with your browser.”

I checked logging but there was no problem. I installed nextcloud 13.0.5
Any idea?

You’d probably need to check your webserver log files. They should be provided by your hoster somewhere (specific folder, customer interface, …). Could be related to some limitations or timeouts (e.g. database connection) or something else.