Losing internet access when creating ethernet bridge for OpenVPN

When you do bridging with OpenVPN, you'll junction your existing eth0 and tap0 into a bridge br0. This is the right thing to do if you want OpenVPN clients to be part of the same network eth0 is in and allow broadcast traffic to traverse.

When the eth0 and tap0 are in a bridge, they are now like ports on a switch, their individual IPs don't matter anymore. You lose internet connection because br0 has no IP now.

br0 is now your NIC and it now needs an IP, either through DHCP or manually assigned. Try dhclient -v br0.

If you don't have a DHCP server running you need to set one up, just for br0 (it's possible to tell isc-dhcp-server to only give out IPs on interface br0 and not your eth0).