If you have access to the G-Portal server admin panel, you can set the value manually by just typing it in.
If you’re doing through the server settings slides in-game, there’s a known issue with it while using a controller in which it only lets either the max or min value to be introduced. In that case we’ve fixed that issue in our Testlive branch and it will be released on all platforms once it has undergone a few rounds of testing.