VPN won't work with Netgear DM200

[duanejoh]

I've got a DM200 that seem to be working great with CenturyLink DSL.  Browsing, video all seems fine.  However, using my work MacBook Pro to connect into the office VPN (using GlobalConnect) isn't working.  With the VPN disabled the internet is fine.  Enable the VPN software and I can no longer get to web sites, including the internal office sites.  Disable the VPN and the internet is fine again.  The VPN software seems to connect and can see our internal sites.  It looks like the inbound packet count never changes; it starts at 7 and never changes.

The office service desk swears that the software is installed correctly.  Since it's part of the standard image that use to format the machines I'll assume that they are correct.  I've tried changing all of the modem/router settings, but nothing seems to help.  And it's a modem/router problem as I've connected the modem directly to the laptop to eliminate the swwitches and WiFi that I have here.  Anyone ever seen this or have an idea what settings I can try?

[dickieblack]

I have this same problem. I just installed an DM200 to act as modem + router instead of my ISPs bundle device (which is poor and randomly stopped working). 

The first thing I noticed was that my VPN to the office stopped working. The VPN connects, but i cannot get connected to any company systems, or anything else - it looks like traffic is not getting back to me.

The DM200 is plugged into a Netgear gigabit switch. Everything i have tested is on a wired connection to rule out wifi issues.

I also have a problem with the BBC iPlayer app on one of two smart TVs, which worked previously. It still works fine on my laptop. I canb't help suspect the two are related and I have enough netowrlking knowledge to suspect that there might be an issue with outbound ports not being opened in some way, or an issue with inbound NAT.

Does anyone have any ideas that could help?

Thanks,

Richard Black

[TheEther]

It could be an MTU problem.  Page 53 in the manual talks about setting the MTU appropriately.

[dickieblack]

Hi, thanks for the quick response.

i've just changed my MTU from the default 1492 down to 1472 to see if that helped, but unfortunately it hasn't made any difference, so i've set it back again.

I've also tried changing the NAT filtering mode from Secure to Open and back again. This too hasn't helped. I've unticked the "disable IGMP proxy" box (so proxying is on, I assume) and disabled th SIP ALG. There don't seem to be many other settings I can change.

If I wait long enoyugh, my VPN connection drops and reconnects, with an error about being unable to send controller heartbeats - this makes sens since no traffic is coming accross the VPN at all.

Now, if i set the DM200 to modem only mode and then connect it to my ISP VDSL router, configure that for Ethernet Routing mode and PPoE, it connects fine. And my VPN works. But loads of other stuff doesn't. Netflix and BBC iPlayer fail on all my smart devices (but still work on a windows laptop).

If I plug the router directly and set it back to its ISP settings, everything works - Netflix and VPN etc - but i still have the poor quality connection I bought the DM200 to fix!

Any suggestions? I can't see anything on my VPN manufacturers support site relating to this.

Richard

[TheEther]

Changing NAT filtering, IGMP proxy and SIP ALG settings won't help.

A controller heartbeat is probably an attempt to inform the remote end of the VPN connection that the local end is still alive.  That's not unusual and a common practice.  It's possible that the heartbeat is being sent precisely because no traffic has been received from the far end.  It sorta a "Hey, I haven't heard from you in a while, but I'm still here!"

Try dropping the MTU to a really low value, like 1400.  If the VPN starts working, then bump up the MTU to just below where it stops working.  If MTU turns out not to be the problem, then you may have to delve deeper into the VPN software's logs for some clues.  The only other possibility I can think of is that the DM200 could be blocking VPN traffic.  Older Netgears used to have a VPN Passthrough setting to control that.  Netgear removed that setting some time ago and defaulted to passing all such traffic through.

[dickieblack]

Thanks again,

I've tried this  just now and even down to 1400 didn't help. I've also done some digging into the connection properties whe nthe VPN is up and i can see the VPN virtual adapter has its own MTU setting (which i can't change). This is 1404, so i've also changed my router MTU to 1410 - i think its right that the bigger number needs to be on the downstream devices - but that alsoi hasn't worked.

Also, looking at the ISP router settings when its being used for the VDSL connection, it has an MTU of 1492 and that works fine with my VPN. I can't find any reference to VPN passthough in the settings or manual, so I guess its not a specific settings on this model. I'm using the latest firmware (1.0.0.44) too.

Richard