Debian – After configuring OpenVPN in bridge mode the serve becomes unreachable from an outside network

I have configured a Debian server with OpenVPN in bridge mode according to OpenVPN's ethernet bridging guide. As part of the guide I ran the bridge-start script which creates a bridge and tap interface. After running bridge-start and openvpn, I can't access my server from an outside network, even though I was able to before running bridge-start. After running the script I can only reach the server if I am on the same internal network. The bridge setup looks correct and has the correct IP address.

I don't think this is a firewall issue, as I don't have any iptables rules set. I can ssh into the server fine if I'm on the internal network, but from outside I get a connection timeout.

I have also verified that packets are indeed reaching the server. So my remote ssh connection fails, yet I see the SSH packets reach the server (using tshark on the server) but they seem to be ignored and the login times out.

How could my ethernet bridge cause my server to become unreachable from an outside network, yet everything works fine on the internal network?

Also, there is a near exact duplicate of this question, although it hasn't been answered and I'm trying to get some visability.

OpenVpn bridge interface does not respond to incoming packets from outer network !