Our customer has TMG 2010 SP2 installed as a two NIC scenario, with Internet-facing NIC in DMZ and LAN-facing NIC in intranet LAN. There are several Nokia E series and Lumia phone ActiveSync clients working OK and able to sync their mail. However, some phones are occasionally unable to sync their mail. Instead, the "Synchronizing mail..." text may hang for two minutes, and then disappear, resulting in 85010014 error on Lumia screen. Typically, the problem phones fail about 50% their sync cases.
The problems started when we replaced the old ISA 2006 server by installing a new W2008 R2 SP1 + TMG 2010 SP2 server from scratch and giving its IP address to TMG. The Exchange server is 2010 SP1 (14.01.0393.000). There are two DC's (W2008 R2, DFL 2008 R2) in LAN, and they are reachable from TMG.
We have tried two different authentication options in the ActiveSync Listener in TMG: both of the Windows (AD) authentication and the LDAP (AD) authentication. The result was that, when the Windows (AD) authentication option was changed to LDAP (AD) option, part of the phones seemed to start sync their mail without problems. However, not all.
When sniffing the network traffic and TLS conversation between Lumia and TMG, we could see that in the timeout case, the TMG is the last one that sends a TLS packet to phone, and then nothing can be seen on that line. However, not sure if this is a relevant finding when solving the actual problem.
What should be done to resolve this issue?
Br, Kari