I'm using True ADSL and I get really good download speeds when I connect directly from my laptop, around 2Mbps. When I use my company's VPN, the download speeds drop drastically to 70Kbps. I've looked around the WEB but so far have not come up with a solution. I do use a Belkin ADSL wireless router to connect. I think it might have something to do with MTU size or how the Belkin handles the VPN, but I am not sure. Tomorrow, I'm going to go over to a friend's house that uses a Linksys router to test if the VPN connections does the same thing there. Also, the upload speeds appear unaffected by the VPN, it just affects the download speeds.

I have used this same laptop in the US with a Netgear router and cable modem, so I know it works fine there using the VPN. Is there something with ASDL and VPNs?

Anyone have any ideas?

Although you should see some drop in performance, (you can’t do better than you corporate upload bandwidth) the drop your getting is bigger than normal. I’ve had the same problem with True ADSL twice and the answer was the same both times – a problem in True’s network. I think it was a faulty router. All you can do is call them up and explain your problem. Make sure to get some one from tech department, not just a customer care agent. You need to follow up you conversation with an email.

The first time it was out for 2 weeks, and it affected a large number of users. I only got them to admit it after I send them a fairly lengthy traceroute analysis that proved it was their problem. The second time only took a call and an email, and it was back in a day or so. Both times the engineering department made follow-up phone calls to make sure every thing was OK.

Good luck,

You had the same problem where a normal connection was fine but the VPN was slow? I have a hard time believing it is an issue with True since I would think this uses the same connection but I could be wrong. I've got a few other tests to try yet and then I will contact True to see if they can help. Thanks for your response!

Well, I think you are right about it being True's fault. I'm only getting 50K to 90K testing outside of Thailand with or without using the VPN. I was confused before since I am using a proxy server inside of Thailand which makes it appear the internet to the US is fast. But when I use the VPN, it bypasses that proxy so my speed drops drastically. It appears that True (or someone) is limiting my bandwidth outside of Thailand.

There is most likely a bandwidth cap on the VPN port. Do you know if your VPN is done on a dedicated port, or as http/https traffic? Also, does it limit corporate traffic download speeds ony, or everything?

You had the same problem where a normal connection was fine but the VPN was slow? I have a hard time believing it is an issue with True since I would think this uses the same connection but I could be wrong. I've got a few other tests to try yet and then I will contact True to see if they can help. Thanks for your response!

Yes, that is exactly what happened to me. The normal connection was fine, and the VPN was slow, regardless of the site I was downloading from. I don’t fully understand the technical details, but it has to do with the difference in data packet size between a normal connection and a VPN connection. A router at true is configured incorrectly, so it had problems processing the different packet size. At least that is how I understood it.

I found that my company has a VPN gateway in Bangkok so I am using that. The funny thing is that I get better speeds to it during off hours. Probably when everyone at work goes home. So during the day I use some other VPN gateway and at night I use the one in Bangkok. I think this should work out for me. I did a traceroute to the Bangkok VPN gateway and it took a least 12 hops to get there. Geez, talk about going the long way around. Looks like True has a nasty mess of how their routers interconnect.

I did try adjusting the MTU size so the packets sent were smaller, but that doesn't help on the receive side since the MTU is determined by the sender. So whatever the VPN gateway is set at is what goes across the network. So if the size is too big and True isn't setup correctly, then there can be issues.