Nick Howitt wrote:

What sort of devices are you trying to connect to? If they are Windows devices, can you please try dropping their firewalls. Also you could try sniffing the packets on the ClearOS LAN interface, either with tcpdump of a firewall rule, but I doubt if you have a problem as the pings are getting through.

It isn't a client firewall issue. The majority of systems running on the other side are Macs or linux boxes (mostly CentOS 7) with firewall disabled since they are hosting private internal services on a variety of ports for a ton of things.

If we go back to the start of this problem as well - there were no issues with client connectivity between sites when using ClearOS 6. It was the move to ClearOS 7 that started to create this issue - so it is safe to rule out anything on the client side as none of that has changed between when I had a perfectly working tunnel under COS6 and now. Also, it is important to note that when using OpenVPN to do remote client connectivity everything works as expected to all clients at either site - so client configuration isn't an issue.

Nick Howitt wrote:
What may be interesting is seeing the source IP's on the packets as the exit the remote firewall.

I'd be very interested in some example tests that I could run with TCPDump to determine what might be happening. I'm admittedly a bit of a neophyte with the tool and the documentation listed in this thread is open enough that it is hard to determine where I should even start. Internal IP to external IP? All traffic? From where? To where? I'm happy to do any tests recommended to get this sorted.