It continues the time with every attempt

With same IP adress, right ?

«maxLoginAttempt: This is the number of attempts a user has to enter the correct password before he or she gets her or his IP address blocked/locked out.»

https://manual.limesurvey.org/Optional_settings#Security

Yes, the Server is behind a proxy (as many Servers I guess). The problem is that ALL users are blocked out an not only the specific user that entered the password 5 times wrong.

This is probably more like a feature request. Just raise the number of login attempts.
Long term probably a whilelist would be needed.

Whitelist can be easily done via Plugin (have one)

Why is it not possible or so difficult to block the ONLY the specific user who entered the wrong password several times and not the IP. Many/most servers are behind a reverse proxy and always see the same IP-address. In this state of arts, the whole system is blocked for all survey administrators.
Example: If I enter my Hotmail-Password wrong 10 times, the whole Hotmail-system would not be blocked for everybody, but only the account that I wanted to access with wrong password attempts will be blocked (same as GMX, ...).
For my opinion it is a security issue because everybody wo knows a survey admin's login can block the system for all admins.
Maybe we misunderstood.

It is now possible to whitelist IP addresses from the global settings and even in the config file. I am therefore closing this issue.