Issues using HAProxy to front-end Webmail

I'm having more and more issues trying to use Webmail behind my firewall's HAProxy service - it used to be that I would get randomly disconnected, then occasionally the logon would get stuck and clearing cookies resolved that, but now no matter what I tryI can't even log on. I get past the credentials then the 2FA code, and it just sits there with the whirling status.

I think the biggest issue is that MDaemon is not proxy aware and logs all my connections as coming from "192.168.1.1" i.e. the firewall - it doesn't look at the X-Forwarded-For header from the proxy to get the real IP. I reported this a very long time ago through the beta list but it's still not been implemented. This is what happens from the MDaemon side:

)Mon 2019-08-12 09:54:05.105: Remember Me token set for ferd@star-one.co.uk (IP 192.168.1.1)
)Mon 2019-08-12 09:54:05.105: Secure password set for ferd@star-one.co.uk (IP 192.168.1.1)
)Mon 2019-08-12 09:54:05.132: [O***********E] Expiring session OKBNI8964OMPE...
)Mon 2019-08-12 09:54:05.133: [O***********E] Session OKBNI8964OMPE expired.
)Mon 2019-08-12 09:54:05.147: [Z***********9] Session created for ferd@star-one.co.uk from 192.168.1.1.
)Mon 2019-08-12 09:54:05.257: [Z***********9] Unable to find last access IP 192.168.1.1 in the database | MMDB_error: Success (not an error)
)Mon 2019-08-12 09:54:05.258: [Z***********9] Updated login history for user ferd@star-one.co.uk. (IP 192.168.1.1)

Today I was checking the the logs for the session and I spotted this:

)Mon 2019-08-12 09:54:05.487: [Z***********9] Unable to expand: CALENDAR.

I also saw this when using the browser console to see what was happening:

)WorldClient.dll?View=Main:967 Uncaught TypeError: Cannot read property 'updateExternalCalendars' of undefined at WorldClient.dll?View=Main:967

Perhaps this is the reason for my current inability to get into webmail, perhaps you can advise how I can clear this error.

P.S. why this forum editor from the stone-age keeps changing my ")" to ")" above I have no clue and after 3 attempts I give up.
P.P.S. I give up, I can't even type a great-than sign without it changing to a bracket.