I have come across a strange issue and was wondering if anyone here had seen this before, and if so had any ideas on what to do next/where to look.
We are having problems with PPTP pass through on 857's using XP clients.
We have a mix of 837's and 857's. Both essentially run the same access rules with only minor differences due to the IOS differences of these devices.
The routers are configured with NAT and hosts on the inside (ethternet) establish a PPTP VPN session with a Windows 2000 SP4 RRAS server located on the WAN (ADSL) side.
Windows 2000 and XP clients behind the 837's have no problems establishing the PPTP session.
Windows 2000 clients behind the 857's have no problems establishing the PPTP session.
Windows XP clients behind the 857's are unable to establish the PPTP session 99% of the time, but very occasionally can. In fact you can have an XP client and a 2000 client connected to the same 857, the 2000 client can consistently connect whilst the XP client has serious issues.
Initially we thought this to be an XP configuration issue (it still could be), but we have tried SP1 and SP2 XP machines, and if you make no changes to the XP client, other than replacing the 857 with an 837, the XP client can then consistently connect - so we are now suspecting something odd with the 857, but given 2000 clients work it is very odd.