B593 VPN issues

chewed

Just posting this here as well in case anyone has any suggestions.

Original post on Ask 3
http://www.boards.ie/ttfthread/2057604844

Since last week I've noticed that when I try to connect to my company's VPN, my internet connection drops completely. As soon as I disconnect from the VPN my Internet connection is back up again. This only started happening last week.

I tried rebooting the laptop and resetting the router back to the factory settings, but nothing seems to work.

I've been using VPN from the house for over a year now and never had any issues. I even tried on a different laptop and the same issues occur on that too.
My IT dept cannot fix the issues either and have suggested I get in touch with 3 about it.

I have a B593 router. Are there any settings I need to change in order to get this working?

Has anyone else experienced any similar issues with their VPN? I use Express VPN and don't have any issues. My IT dept have told me to get in touch with 3 as they think it's a router issue.

editorsean

One good possibility is a side effect of Three recently reducing its MTU size. It was 1500 and now seems to be 1446, at least at my end.

If the MTU size is not set correctly, generally a VPN connection will establish, but provides no Internet connectivity.

As the MTU size can vary from location to location (e.g. in Letterkenny it's the low 1300's if I recall right), I would suggest working it out as follows:

1. First start by bringing up a command prompt and type in: ping -n 2 -f -l 1400 8.8.8.8

2. If you get "Request timed out" or "Packet needs to be fragmented..." results, try with 1300 instead of 1400.

3. Re-run the command but with the 1400 (or 1300) value increased by 10 and keep doing this until you either get "Request timed out" or "Packet needs to be fragmented..." results.

4. Now decrease the value by steps of 2 until you get ping replies again. The following shows an example from my end:



5. Add 28 to this value to get the MTU size. In my example, 1418 was the highest figure that gave ping replies, so 1418 + 28 gives an MTU size of 1446.

6. Go into your router's configuration, click the "Internet" Tab and then go into "Internet MTU" on the left. Put in the resulting MTU size and submit it.

In case Three later fix this, e.g. go back to the original 1500 MTU size, I would suggest periodically trying the original 1500 MTU size to see if the VPN has internet connectivity as a lower than necessary MTU size can have a negative impact on the overall performance of the connection.

chewed

hi editorsean, thanks for the suggestion.

Before I try this, should I have the VPN connected or disconnected before I try the ping tests?

editorsean

This needs to be done without the VPN connected.

If you know the hostname or IP address the VPN uses, you can try pinging it to see if it replies to ping requests. If it does reply to pings, run that process with that hostname or IP address instead of 8.8.8.8 which is the Google DNS IP address, again with the VPN disconnected. This way if a lower MTU size is required to reach the VPN server, you can put this in the router instead.

chewed

I tried this today, but unfortunately had no luck. I found out 1370 was the highest I could go without getting a timed out message. I added 28 and set it as 1398 in the MTU settings. I then logged back into VPN and again, my connection completely dropped.

my3cents

The MTU size issue is the long time three issue that messes up VPN's and HTTPS I alluded to in the other thread.

I wouldn't say three had recently reduced the MTU size as I can trace the problem back at least five years.

However for some reason I've never been able to work out the issue seems also to relate to the router at the clients end. The problem was most noticeable with the B260a (EDIT> which three refused to acknowledge). I often get an issue with BoI where I can get to the login page and my credentials are accepted but just get stuck at the point.

I'm also not sure you can be 100% sure of any tests for MTU size? I believe that different traffic (https http etc) is routed differently so you could test one route with a ping test only to have your data go (or return) on a different route.

chewed

As I mentioned also, I never had this issue up until 2 weeks ago with VPN access. I've been using the same Router and Laptop for the past 8 months. So, it must be something 3 have changed?

my3cents

chewed wrote: »

As I mentioned also, I never had this issue up until 2 weeks ago with VPN access. I've been using the same Router and Laptop for the past 8 months. So, it must be something 3 have changed?

I don't think three have changed anything. All data goes somewhere and the route is dependent on how you are connected, starting point, end point, traffic type and load on the network so it just could be that when the network has a particular load on it your data gets routed through a circuit that has a lower MTU size.

Don't forget I said I can find history for this issue going back at least 5 years and same thing was reported then, a connection normally https to a particular site that was working then stopped working.

Its far easier just to generalise and say three is flaky, at least in that nothing has changed.

chewed

my3cents wrote: »

I don't think three have changed anything. All data goes somewhere and the route is dependent on how you are connected, starting point, end point, traffic type and load on the network so it just could be that when the network has a particular load on it your data gets routed through a circuit that has a lower MTU size.

Don't forget I said I can find history for this issue going back at least 5 years and same thing was reported then, a connection normally https to a particular site that was working then stopped working.

Its far easier just to generalise and say three is flaky, at least in that nothing has changed.

So, is this something my IT dept should be able to fix? They have already informed me to contact 3, as it's a router issue! I'm just not sure where to go with this. It's the difference between me being able to work from home or commute 2 hours in and 2 hours home each day.

Could it be the laptop settings? Should I get another work laptop to test it?

chewed

Quick Update. I read somewhere to try and reset the Router back to Factory settings. So tried this and it seems to be working now!

my3cents

chewed wrote: »

So, is this something my IT dept should be able to fix? They have already informed me to contact 3, as it's a router issue! I'm just not sure where to go with this. It's the difference between me being able to work from home or commute 2 hours in and 2 hours home each day.

Could it be the laptop settings? Should I get another work laptop to test it?

Sorry but the answer is simple use anyone other than three.

I know its harsh but if they are all you have then you can't reliably (or at all atm) work from home.

Only other option if there is no one else is satellite the cost of which would be cheaper than commuting but even then you will need to keep it just for work due to usage caps.

Given my past experience of issues with three I have every confidence that your issue will eventually go away and come back again. Its also worth trying a couple of different second hand mifi or wifi devices. Borrow one and test if you can. If a phone works then get one just for use as a hotspot and use it with a prepay €20 ayce data phone topup

my3cents

chewed wrote: »

Quick Update. I read somewhere to try and reset the Router back to Factory settings. So tried this and it seems to be working now!

The obvious deduction from that being it was something that YOU did but I'd doubt that because I have seen the problem crop up for no apparent reason.

chewed

my3cents wrote: »

Sorry but the answer is simple use anyone other than three.

I know its harsh but if they are all you have then you can't reliably (or at all atm) work from home.

Only other option if there is no one else is satellite the cost of which would be cheaper than commuting but even then you will need to keep it just for work due to usage caps.

Given my past experience of issues with three I have every confidence that your issue will eventually go away and come back again. Its also worth trying a couple of different second hand mifi or wifi devices. Borrow one and test if you can. If a phone works then get one just for use as a hotspot and use it with a prepay €20 ayce data phone topup

Well, the good news is that we're down to get FTTH eFibre broadband at the end of the year. So I will have to hold out until then. At least I can use my phone as a tether and get connected if all else fails.