I have two ERPOE-5s sitting on my desk right now that I'm trying to set up for PPTP VPN access, and there's some odd behaviour on one that isn't happening on the other. Both are running firmware 1.9.0, and the PPTP VPN settings are largely-similar on both as they were configured using this guide.
On the first router, everything VPN-related is up and running and has tested out successfully.
On the second router, the VPN configuration appears to have committed without errors. However, no pptp0 interface is created; `show interfaces` bears this out. pptpd is starting and appears to be running, and there are no errors for it in /var/log/messages.
In both cases, pptpd is being asked to bind to the WAN interface (eth0), which is receiving its address configuration via DHCP. The only real difference there is that one address is coming from a /19 pool while the other is from a /24, but that shouldn't matter.
At this point I'm at a loss to explain why the pptp interface is being created on one of the devices but not the other. Multiple reboots have failed to cause it to come up. Doing a factory reset and reapplication of the configuration is pretty much a last resort in this case and I'd prefer to keep it that way for now. Does anyone have any ideas as to where the issue might lie?