You can try to use host names instead of IP addresses. If that's not possible you can only limit the range for dynamic IP address leases in your DHCP server configuration and add host entries for every possible IP address in Veyon Configurator. An automatic discovery plugin for dynamic environments will be available later this year.
If they are on the same network, then try disabling your firewall.
If the connection is successful, try to open ports
Check energy settings to try to solve the sleep mode, it could be an option
do you use server ports other than the default ones (i.e. 11100)? If so please upgrade to Veyon >= 4.0.7 which contains a fix for remote control with non-default ports. If you didn't change the ports you normally shouldn't encounter any problems. Which authentication method are you using? Are you using access control rules?
Thanks for your feedback! It's currently not in work as the initial idea was that such operations usually are performed by scripts and thus no graphical frontend was required. We might however add this in the future but I can't make any promises yet. Feel free to make a donation in order to prioritize the implementation and show the importance for you Code contributions are welcome as well.
Thanks for fixing that in a future release.
The message box shouldn't be a problem (and could be a indicator that it works). Custom positions is not that important - to fix the zoom level will be enough.