Last Friday I finally changed ISP from OneTel to TalkTalk. It has taken a bit longer than I thought when I originally wrote about it. I originally thought I would switch from OneTel to British Telecom. However, this was complicated because my line is rented from OneTel. BT are very good at sending junk mail and phoning at inconvenient times (even though we are ex-directory) to try to persuade me to switch back to them. They have been doing this ever since I first switched to OneTel. They claimed they would handle the business of getting some magic number that was needed to switch the line back, but when it came to the crunch they were completely lame and nothing happened so I gave up the idea for a while.
A couple of weeks ago I was getting long pauses "looking up google.com" and other sites and started getting discontented again. I looked at the results of broadband speed checks in my area and found that many people were getting faster speeds than I was. Some of those with the highest speeds were using TalkTalk. OneTel was taken over by TalkTalk a couple of years back but I had never been offered an upgraded package and I discovered I was paying more for a 2Mbit/s broadband service than TalkTalk was charging for a 24Mbit/s service. So I phoned them up and asked them to switch me to the TalkTalk Pro package.
I was very impressed with the way the changeover was handled by TalkTalk. I was sent plenty of information updating me on the progress of my order and also received several days in advance a free D-Link wireless router preconfigured with my account details. However I wanted to use my existing Draytek Vigor 2800VG router which has built-in VoIP support (which I use for a second phone line) and the ability to use a 3G mobile broadband USB modem as a backup for the ADSL. So I connected up the D-Link and copied all the settings from it (fortunately the password was shown in clear) ready to enter into the Draytek.
Changeover day came on Friday. The old broadband connection was down, so I typed in the new settings and was swiftly connected to TalkTalk. After a bit of trial and error with the modulation type I found the fastest setting and everything seemed to be working. Until I tried to access Gmail. After log-in to my Gmail account the browser froze for a minute or two then displayed a blank page. This happened repeatedly, using any PC. Disconnecting TalkTalk so that the router fell back to the 3G connection allowed Gmail to be accessed with no problems, so clearly this was a problem with TalkTalk.
Some serious Googling ensued. There seemed to be an issue with TalkTalk, Gmail and the MaxMTU setting. MTU means "maximum transmission unit" and it determines the maximum size of a packet that can be sent over the internet. If it is set too large, a packet has to be split into two or "fragmented". This is bad for performance, but it appears that often it doesn't arrive at all. The normal MaxMTU setting is 1500, but TalkTalk's router was set for 1432. I tried setting the Windows MaxMTU to that value using the DrTCP tool but it didn't help. I even tried some smaller values but still got nowhere. Clearly I was going to have to get support from TalkTalk, but I guessed they would put the blame on my router unless the one they supplied also had the problem, so I thought I had better try it.
When I connected TalkTalk's D-Link DSL-2740R wireless modem router there was no problem accessing Gmail. This was a bit frustrating. I didn't want to give up the Draytek and do without my VoIP second phone line or my 3G backup but it looked as if I was going to have to use the D-Link. I then tried testing other things that we use on the Internet and found that both of the laptops which run a Linux distribution called Xandros could not connect to the wireless at all. I also found that the Reciva-based wi-fi internet radios reported trouble connecting to the Reciva website, complaining that a port was blocked even though I hadn't touched the firewall settings.
I decided that I would have to use the Draytek, which is what I wanted to do anyway, so I started searching their support forum. There I found someone else had experienced the problem with accessing Gmail through TalkTalk and found the solution was to reduce MTU on the router to 1200. For the benefit of anyone else that has this problem, you do this by logging in to the router using Telnet and entering the command wan ppp_mss 1200. Who would have guessed it? Now I can apparently access all websites, everything else is working and I'm a happy bunny.
Or at least I was until this afternoon when I went back to the broadband speed test site and ran some new speed tests. TalkTalk's sales people reckoned that from my location I should be able to get about 13MBit/sec. Using my Draytek Vigor 2800VG the maximum download speed I can get is only 8MBit/sec. Using TalkTalk's supplied D-Link router I can get nearly 11.5Mbit/s.
I suppose it doesn't really matter. The wireless laptops can't transfer data that fast anyway. Neither can the one hard wired PC - the old Acer in the office / radio shack - because its network card is normally set to 10Mbit/s due to the fact that when set to 100Mbit/s it radiates a strong carrier right on the 2m FM calling channel.