Suddenly can't connect to VPN via O2 dongle anymore

brcwatters

I live in no-broadband land and use an O2 dongle which isn't too bad. I work from home and use a vpn to connect to work - somedays I work almost entirely on the vpn and then other times I'll only go on once or twice a week. Have been working away on this fine for now - I could either plug the dongle into a router or directly into the laptop and it all worked fine.

Around last Wed or Thursday thought it stopped working, for no apparent reason. Getting an 800 error. I have brought the laptop to the local hotel and used their wifi and was able to connect to the vpn fine like that, but I can't work there all the time! So does it seem like an O2 issue if it works from one connection but not the O2 one? Or is there something else I can check. Work have checked their end and nothing has changed.

I talked to O2 tonight and they just said to change to open.internet.public and did one of those remote reboots. Did that, no change. The sim card is relatively new, only this year I think, or late last year.

Thanks

eirator

tbh there's nothing much you can do, its probably due to O2's routing which may or may not change again.

You might possibly try changing your MTU - google MTU for more info. What I think might be happening is that your connection is going through a VPN already on O2's network and this can restrict the size of packet that can be transferred (MTU) and then you add your own VPN so your data packets with all the VPN header overhead won't fit down the first VPN. If you can ping your VPN server and use the -l and -f switches you can work out the maximum size of packet you can send and check if its lower than it should be.

>ping vpnserver.name -f -l 1412

then reduce or increase the number at the end until you get the max you can without fragmentation then see if its the same as you get on the Hotel WiFi

............but that may be a total red herring and totally inconclusive

brcwatters

Thanks eirator. I can't however ping the server. Work says it won't respond to ping. But I can get in to office webmail on a browser which is on the same server.

Actually I'm in the library this morning and it's not working on their wifi either so it might not just be an O2 thing. Have been playing around with advanced settings on firewall - GRE and PPTP settings - but not making any difference. Going to have to find a networking head around here to bring it in to I think. I'm a bit out of my league - css and jquery is my thing, haven't a clue about networks

eirator

I would expect the library WiFi to go through a more than necessarily secure firewall, content filter and possibly a lot of internal routing so it might not work with a VPN unless it has previously?

If you can try the ping with the -f and -l swtiches to any server on your works network from various external networks you can see if the MTU varies.

You can also use TCP Optimiser downloadable from http://www.speedguide.net/downloads.php and just use the MTU/latency tab to check the MTU to you work network iirc 1412 is normal.

Could also be port blocking, particularly in the library, check with your support guys what ports your VPN uses and what tool you can use to check if the port is open, a port scanner just checking the specific ports might shed some light on the problem. There will also be a way of getting a debug log from your VPN client when it connects or doesn't so you can see what is failing. Best to get a log of what happens when it does work and compare that to one where you fail to connect.

jimmycrackcorm

What vpn are you using? I've had issues with cisco vpn client which worked and then I had to make a client configuration change when it stopped suddenly working.

brcwatters

Thanks for your help jimmycrackcorm and eirator. I went into the Talk to O2 boards (never knew they existed, very useful) - and immediately saw someone with a similar problem. Kinda piggybacked on his thread and we both got sorted today. So relieved I can actually work tomorrow and not have to take holiday day to wander around Navan stocking up on various dongles to find one that would work!

ecooney

I'm having the same problem.

BRCWATTERS - Would it be possible to link to the thread that sorted the issue for you?

eirator

ecooney wrote: »

I'm having the same problem.

BRCWATTERS - Would it be possible to link to the thread that sorted the issue for you?

I looked it up when he first posted iirc the fix was to change the APN, you'll have to check what was the correct one though.

brcwatters

Hi ecooney. I had to change the APN yes (Tools > Options > Profile Management > New etc), but I had done that already and it hadn't worked, and O2Lisa told me to turn off the dongle for 10 minutes so they must have done one of those remote reboots or something to it. The guy on the phone the night before had done this as well but it didn't work, but somehow what she did sorted it out. The thread is at:

http://www.boards.ie/ttfthread/2056937817

and the APN is open.internet.public. That Talk to O2 forum is handy, I hadn't known it was there. I think it's better than ringing O2 directly, so if changing the APN doesn't work for you it might be worth starting a new thread there. Hope this helps!