I found myself facing a strange issue while moving from my simple all-in-one VPS server to a more roomy Kimsufi 16G running ESXi 5.0.
I only have one IPv4 address so I am using Sophos UTM 9’s Web Application Firewall to spread out some sites to different backend servers.
This is working fine, I did have to switch to basic protection for Zimbra Webmail but that’s really a non-issue.
However during the IPv6 push I made yesterday, Zimbra Webmail went FUBAR in Firefox. Worked fine in Chrome and Safari.
After about 3 hours of troubleshooting were I went over all the possibilities (Maybe Firefox mixed IPv4 and IPv6 requests, …).
I tried disabling IPv6 on my local UTM. Firefox worked again :S disabling IPv4 and forcing IPv6 was broken.
Now satisfied it was not a Firefox issue, I zoned in on the reverse proxy. Because I run Z-Push I can’t use Zimbra’s Webmail directly.
After first simplifying my setup and forcing Zimbra to only serve on [::1]:8080 and reworking my reverse proxy and z-push configs I was confident nothing on the Zimbra end went wrong.
# Zimbra Webmail enconding hotfix AddEncoding x-gzip .js.zgz AddType application/gzip .js.zgz
Restarted HTTPD and… nothing! I then cleared the Firefox cache and bingo! It is working again.
Hopefully this is useful for some of you out there!