Well, I have searched the threads high and low and thought I was the only person experiencing these issues.
I am experiencing similiar situation except have made a little progress. My configuration:
Laptop -> Linksys BEFSR41 DSL/Cable Router (PPoE connect) -> Westell Dsl - ADSL (750/128 kbps) Verizon Internet -> Work VPN Gateway.
All connections work fine to the Internet.
When I esablish a connection through VPN software to the network VPN connects and autheticates but intermiitently and randomly drops the VPN connection. I have experienced this issue using both Secure-Remote SP 4.1??? or higher (the one that's supposed to work over NAT) as well as with Microsoft VPN DUN.
Just two nights ago I connected directly to the VPN without using the Linksys Router. I had to reinstall verizon's WinPoet PPOe software. The connection held strong with this direct method
I upgraded the linksys router firmware to the latest version on the linksys website and re-introduced the router into the equation. The VPN connection now works consistently!
Questions for anyone?
1. The current PPOE software is still installed? is this helping the VPN connection?
2. Is the latest firmware upgrade fixing the issue v 1.44?
3. Will my securemote connection now actually connect throught the router? (laptop at work - can't try tonight)
In order to get the configuration working I needed the following setup in the linksys router:
MTU - Enabled 1492 (all connected computers to LAN NO Registry tweaks on MTU - see speedguide.com)
Pass Through enabled for IPSEC and PPTP.
These where the key issues. Although the linksys.com knowledge base pages suggested forwarding ports 47 -> 1723 and 50 -> 500. Frankly this didn't make any difference in my setup.
Additionally, the wireless function is something I haven't played with yet. I think there may be some general config issues with WEP. But if the laptop, connected through wireless, can access the internet, there shoouldn't be a problem as far as I am aware. If anyone out there knows more about wireless, WEP, and VPN - much appreciated.
Good luck and let me know