I am managing to use VNC with the RealVNC client under bookworm. There are some confusing 'features'
One, referred to here: viewtopic.php?p=2346327#p2346390 is that logging on or off on the remote desktop drops the connection. In the past I always left the remote desktop at the login prompt because of the (now removed) outrageous ability to connect as a different user and pick up an existing desktop session.
There is a short time (maybe only a couple of seconds) during which attempts to reconnect fail and get the client showing authorization failure messages. In my case some - but not all - of the time it was because the client was alternating between UDP and TCP on the VNC port trying to get a response and getting blocked by a LIMIT IN setting in the firewall. I guess fail2ban might cause the same.
Trying another username at this point fouls the whole thing up until I close the client and start again with the original one. It's hard to work out which username and password RealVNC is trying to use. I think it may remember one in its address book/bookmark feature. Which can cause a problem if the remote desktop is logged in.
Some times on the first attempt of the day I get an authorisation failure with correct username and password. The solution then is not to use the address book but to type the remote IP address into the address field.
Usually with a failure RealVNVC gives two prompt windows with click buttons at the same time. Hard to deal with - I think the one underneath may have focus.
TL;DR Only use one username, be patient after a dropped connection, leave the remote desktop logged in if that's safe where you are.
One, referred to here: viewtopic.php?p=2346327#p2346390 is that logging on or off on the remote desktop drops the connection. In the past I always left the remote desktop at the login prompt because of the (now removed) outrageous ability to connect as a different user and pick up an existing desktop session.
There is a short time (maybe only a couple of seconds) during which attempts to reconnect fail and get the client showing authorization failure messages. In my case some - but not all - of the time it was because the client was alternating between UDP and TCP on the VNC port trying to get a response and getting blocked by a LIMIT IN setting in the firewall. I guess fail2ban might cause the same.
Trying another username at this point fouls the whole thing up until I close the client and start again with the original one. It's hard to work out which username and password RealVNC is trying to use. I think it may remember one in its address book/bookmark feature. Which can cause a problem if the remote desktop is logged in.
Some times on the first attempt of the day I get an authorisation failure with correct username and password. The solution then is not to use the address book but to type the remote IP address into the address field.
Usually with a failure RealVNVC gives two prompt windows with click buttons at the same time. Hard to deal with - I think the one underneath may have focus.
TL;DR Only use one username, be patient after a dropped connection, leave the remote desktop logged in if that's safe where you are.
Statistics: Posted by PDM1950 — Wed Nov 26, 2025 8:59 am