Outlook Anywhere - RPC_IN_DATA: failed to read request body

Hi,

I`ve published a few internal services and websites using the Web Application Firewall in UTM 9.2, and this have worked well except for publishing Outlook Anywhere against Exchange 2010 SP3. I used the following guide to configure the publishing of Outlook Anywhere (using Basic authentication):
https://sophserv.sophos.com/repo_kb/120454/file/Configuring%20UTM%20firewall%20for%20Exchange.pdf
I use https://testconnectivity.microsoft.com for testing the published application.
From the testconnectivity.microsoft.com website I get the following error when testing Outlook Anywhere: RPC_S_SERVER_UNAVAILABLE (0x6)

In the Web Application Firewall Log I see the following entries logged while performing the test:

2014:10:06-00:25:32 FW-01 reverseproxy: id="0299" srcip="134.170.52.122" localip="109.247.18.28" size="58" user="-" host="134.170.52.122" method="RPC_IN_DATA" statuscode="401" reason="-" extra="-" exceptions="SkipURLHardening" time="9313507" url="/rpc/rpcproxy.dll" server="outlook.mydomain.com" referer="-" cookie="-" set-cookie="-" 

2014:10:06-00:25:33 FW-01 reverseproxy: id="0299" srcip="134.170.52.122" localip="109.247.18.28" size="58" user="-" host="134.170.52.122" method="RPC_IN_DATA" statuscode="401" reason="-" extra="-" exceptions="SkipURLHardening" time="6234" url="/rpc/rpcproxy.dll" server="outlook.mydomain.com" referer="-" cookie="-" set-cookie="-" 

2014:10:06-00:25:33 FW-01 reverseproxy: id="0299" srcip="134.170.52.122" localip="109.247.18.28" size="20" user="-" host="134.170.52.122" method="RPC_IN_DATA" statuscode="200" reason="-" extra="-" exceptions="SkipURLHardening" time="30533" url="/Rpc/RpcProxy.dll" server="outlook.mydomain.com" referer="-" cookie="-" set-cookie="-" 

2014:10:06-00:30:34 FW-01 reverseproxy: [Mon Oct 06 00:30:34.646489 2014] [proxy_msrpc:error] [pid 1100:tid 3929434992] (70007)The timeout specified has expired: [client 134.170.52.122:52017] RPC_IN_DATA: failed to read request body - ap_get_brigade 

2014:10:06-00:30:34 FW-01 reverseproxy: id="0299" srcip="134.170.52.122" localip="109.247.18.28" size="0" user="-" host="134.170.52.122" method="RPC_IN_DATA" statuscode="400" reason="-" extra="-" exceptions="SkipURLHardening" time="300135708" url="/rpc/rpcproxy.dll" server="outlook.mydomain.com" referer="-" cookie="-" set-cookie="-" 


Are there any known issues regarding publishing Outlook Anywhere with Sophos UTM 9.2? 
If not, do you have any ideas what might be the issue in my setup?

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