CentOS and Red Hat add a few complexities on top of the “plain” Debian-based Linux distros one may be more likely to run on a laptop or Raspberry Pi. SELinux in particular is another layer to consider.
For SSH connection problems, suggest setting /etc/ssh/sshd_config to have
systemctl restart sshd.service
and try to login. This will print a good amount of information streaming and helps reveal .ssh/authorized_keys permissions issues and more.
In general, if one is puzzled if SELinux is causing an issue, as a last resort one may temporarily and carefully edit /etc/selinux/config to have
Be sure to put that back to
enforcing and reboot when done.
Check that firewalld is allowing the desired SSH port through.
tcpdump port 22 -n -Q inout
should show packets from the client–if not the SSH server firewall may be blocking them.
For VNC in general we avoid the fancy graphical desktop. To use the 2D simple “classic” desktop on VNC, edit ~/.vnc/xstartup to have:
before the “xinitrc” line.
To check VNC server status:
systemctl status vncserver@:1
If VNC isn’t working for a user, check that their username is specied with a display number in file: /etc/tigervnc/vncserver.users