Managed to resolve my issue by adding the following:
pre-up iptables-restore < /etc/network/iptables.rules
to
/etc/network/interfaces.

Output of iptables commands pi@raspberrypi:~ $ sudo iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination pi@raspberrypi:~ $ sudo iptables -t nat -L C...

Never knew DNSMasq was a DHCP Server
Will uninstall isc and config dnsmasq as the dhcp server
Will check the out put of the iptables command

Have a Pi 3B+ with latest Raspbian Buster with desktop installed Have also installed a USB to ethernet dongle Have installed and have up and running Isc-dhcp server Dnsmasq Openvpn Network config is as follows: ADSL modem -> eth0 RPi ----> eth1 Pi -> switch -> home PC’s I have followed a guide on th...