Rustdesk – an Open Source, Self Hosted alternative to TeamViewer, AnyDesk, GoToAssist, and the like.

Make sure you open these ports:

ufw allow 21114:21119/tcp
ufw allow 8000/tcp
ufw allow 21116/udp
sudo ufw enable

Disable iptables

iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -F

iptables --flush

Also enable the ports in the default security list for the subnet.