My home router is a small and crappy SMC Barricade SMCWBR14S-N4. It's pretty cheap and nasty but at least it runs BusyBox (from factory).
The main problem: I can't connect to VPNs (PPTP). The more exact problem: GRE packets not passing through - the initial VPN connection is fine, auth is fine, then the configuration packets (GRE) don't come back to me. I've double-checked that the problem is, in fact, the router. Without it, connecting directly to the cable modem, everything's fine.
The mystery: sometimes it works in a Ubuntu virtual machine (VMWare). It does not ever work on the Win7 host. It does not work in a Win7 VM. Does not work on my iPhone. How's that for nonsense?
- I've tried enabling/disabling the router's firewall and SPI.
- I've enabled/disabled the DMZ.
- I've resetted the router to factory settings.
- I've tried running the router with specific iptables rules to let GRE (protocol 47) through.
- I've tried running the router with no iptables rules at all (i.e. "let everything through").
So, any idea whatsoever about this? What's pushing my buttons is the "sometimes works with Ubuntu VM" thing. And at one point in the past, it worked fine everywhere! Hurr durr?!