I switched ISP's. I have a block of statics so I reconfigured the Sophos UTM by simply editing the IP address of the external interface and the IP's listed on the Additional Addresses tab. Those are the only settings that I changed.
Everything works fine except that I can no longer access one particular remote server from the LAN. It's actually an email server. I can ping it from the LAN but I cannot access it via SSH, HTTP/S, smtp, pop, imap etc. The issue is definitely with the Sophos UTM. I get the same result if I try to access the email server, from a cell phone, via the Sophos SSL VPN. I get the same failures if I connect a PC directly to the internal interface on the Sophos box.
However, I can access that email server (via any of its open ports) if I bypass the Sophos box by connecting a PC directly to the Verizon ONT so I know its not a matter of the remote server blocking my new public IP addresses.
Anyone have any ideas as to why this is happening? I did not see any drops in the firewall, web protection or IPS logs for that server. I don't have any firewall rules or NAT's specifically for that email server other than having the correct ports open for outbound traffic. I tried rebooting the remote server and the Sophos UTM/box but that did not help. Is there any type of cache that rebooting doesn't flush? The UTM box is actually running ESXi and the Sophos UTM is a VM. I also disabled IPS, Web filtering etc. I do not utilize any of the Sophos UTM Email Protection features for this particular server. Could changing the IP's in Sophos have caused ESXi to be the culprit?
The email server has webmail. I can access it if I configure my browser to use a Shadowsocks proxy with obfuscation. So that traffic does "sneak" through the UTM but the webmail cannot be accessed, on the LAN, without that proxy.
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