Fast Connection Speed - But Some Websites Don't Load Properly

robbo1 · Sep 17, 2009, 22:18:26

Hi there,

I have been with IDNET for about a month now. The connection speed I get on a speed test is excellent (12 times faster during the evenings than my last ISP!).

However, some websites I find it difficult to access. Either the whole page does not load, or nothing loads at all, and it is getting a little frustrating.

I have tried setting a different MTU (was 1500 initially), but it has not seemed to have much of an effect.

Can anyone give any suggestions please.

I am using a 3COM router (3CRWDR100A-72) and I have manually entered the setting supplied by IDNET.

The PC I am using is a MacBook via wireless connection to the above router.

Thanks in advance.

Robbo1

P.S an example of this is that i have had to try reloading the page about 5 times to post this message!

sobranie · Sep 17, 2009, 22:41:29

A quick look at Kitz site will probably sort things out.
Start here:

http://www.kitz.co.uk/adsl/MTU.htm

sobranie · Sep 17, 2009, 22:45:27

Ooops!! Kitz seems to be having probs at the mo., try again later methinks.

Fox · Sep 17, 2009, 23:48:12

I sometimes get a similar problem on a wireless laptop running XP pro, all I need to do to fix it is click the repair connection option in wireless networking but I dont have a Mac so I dont know if that or a similar option is available to you. I would leave the MTU at 1500.

I am sure a Mac expert will be along soon tho

Sebby · Sep 18, 2009, 00:17:54

Hi Robbo, do you know if the situation is the same on another computer on the same connection?

Could you try using OpenDNS to see if that cures it?

It could be an MTU issue. It's worth trying to set that properly as well.

Tacitus · Sep 18, 2009, 08:05:31

Hi Robbo1:

Not sure if you're running Leopard but you can set the MTU as follows....

System prefs -> network -> advanced -> ethernet

If you're running as user you will need your admin name and password to do any changes. I don't have access to a machine running Tiger at the mo, but from memory you will find it in more or less the same place.

FWIW I've never found the need to change it. YMMV

HTH

Simon_idnet · Sep 18, 2009, 11:54:18

What MTU size did you try Robo? I'd recommend trying as low as 1450 (or more even) on a wireless MacBook.
Simon

robbo1 · Sep 18, 2009, 13:27:31

Thanks all,

I tried setting my router back to 1500 and setting it to automatically detect the setting from the ISP late last night.

I will look at the MTU settings on my Mac when I get home tonight and report back with my sucess when I know if there have been any improvements.

Rob

Simon_idnet · Sep 18, 2009, 14:29:42

Your router MTU shoud be set to 1458 or lower. The PC should match or be lower than your router setting (higher will cause dropped packets).

Simon

Fox · Sep 18, 2009, 15:04:06

Simon, my MTU on my ethernet is set at 1500 and the MTU on my router is 1400 (I havent changed them thats just what they are set at by default). As far as I am aware I have no problems with dropped packets etc.

Transmit:

Good Tx Frames 559519
Good Tx Broadcast Frames 266
Good Tx Multicast Frames 323
Tx Total Bytes 549572794
Collisions 0
Error Frames 0
Carrier Sense Errors 0

Receive:

Good Rx Frames 539295
Good Rx Broadcast Frames 1400
Good Tx Multicast Frames 2555
Rx Total Bytes 61957926
CRC Errors 0
Undersized Frames 0
Overruns 0

Should I consider changing the MTU on my ethernet or is it a case of if it isn't broken don't try to fix it

Steve · Sep 18, 2009, 15:19:15

Quote from: Simon_idnet on Sep 18, 2009, 14:29:42
Your router MTU shoud be set to 1458 or lower. The PC should match or be lower than your router setting (higher will cause dropped packets).

Simon

Simon are you suggesting that this be universal setting for all idnet ISP users or is this more dependent on the router/computer combination?

robbo1 · Sep 18, 2009, 19:24:44

Thanks again all,

I have changed my MTU as advised by Simon using the tip from HTH, I shall report back in the next couple of days to let you all know the results.

Posting this seems to be OK and a few speed tests have shown I am connected between 5-6.5 Mb/s which is pretty good.

Fingers crossed

Robbo1

Rik · Sep 18, 2009, 19:28:37

Comms is a black art.

robbo1 · Sep 18, 2009, 19:37:21

The very first website I went to (facebook) took an age to log into. So I changed MTU back to 1500 and it logged in instantly. Then I tried to post back here, and with 1500 it wouldn't get this the idnetters website. I changed it back to 1458 and it logged in here instantly.

I am very confused.

Could it be a problem with my router.

I have been trying to convince the wife that i should get a wireless N router.. (Please let it me the router, please let it be the router)

quandam · Sep 18, 2009, 20:29:05

Quote from: stevethegas on Sep 18, 2009, 15:19:15
Simon are you suggesting that this be universal setting for all idnet ISP users or is this more dependent on the router/computer combination?

Steve and robbo1

If it is any help I had my MTU set to 1500 and reading this thread changed it to 1458 and things appear to be zipping along more smoothly and quickly. I may be wrong of course, it could be in the mind, I could be under the influence of a couple (?) of glasses of excellent red wine but things appear to be a lttle crisper and a little more enjoyable.

Certainly the red wine is enjoyable!

LesD · Sep 18, 2009, 21:02:35

MTU stands for Maximum Transmission Unit. It is the maximum packet size, in bytes, that can be transmitted across a link. If your MTU is set too high, errors will cause each packet to be resent. This can cause issues with the performance/responsiveness of your ADSL connection.

The recommended MTU for use with BT UK ADSL is 1458. If this doesn't improve matters, you can try setting it to 1430.

The recommended MTU for use with ADSL 8 Mb connections should be 1500. If this doesn't improve matters, you can try setting it to 1478.

Determine your MTU

If you wish to acquire what your max MTU can be you can perform the following command in an MS-DOS prompt:

ping -f -l 1472 www.google.com

If you receive a message "packet needs to be fragmented" reduce the value 1472 by 10 and retry, taking 10 away each time until a successful reply is made, then increase by 1 until your one away from receiving the message "packet needs to be fragmented" again.

Add 28 to this value you now have, and you now have your max MTU.

Modify your MTU

To change your MTU setting, you may find a 3rd party application to achieve this or will need to check the following website support pages for guidance. Either way, you do so at your own risk:

Appendix 2 The ping technique at the Command Prompt:

C:\>ping -f -l 1431 www.bbc.co.uk

Pinging www.bbc.net.uk [212.58.240.121] with 1431 bytes of data:

Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 212.58.240.121:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

C:\>ping -f -l 1430 www.bbc.co.uk

Pinging www.bbc.net.uk [212.58.240.31] with 1430 bytes of data:

Reply from 212.58.240.31: bytes=1430 time=136ms TTL=246
Reply from 212.58.240.31: bytes=1430 time=135ms TTL=246
Reply from 212.58.240.31: bytes=1430 time=135ms TTL=246
Reply from 212.58.240.31: bytes=1430 time=135ms TTL=246

Ping statistics for 212.58.240.31:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 135ms, Maximum = 136ms, Average = 135ms

C:\>

Above Information from the Eclipse Knowledge Base sometime ago.

As I recall there are two places that MTU can be set.
The one in the router is the easy one but there is one in Windows too.
There are little utilities out there that can be downloaded. The one in this link is an example not a recommendation so take care.

It may be worth a look here too and at the MS knowledge base article it leads to.

Steve · Sep 18, 2009, 22:20:56

I think I'll leave the Macbook wireless on auto for MTU as I don't seem to have any issues. Still puzzled by simon_idnet comment to set router at 1458 as posted in the other thread I thought it was 1500 for idnet. Certainly on my Windows machines were not seeing any packet loss with 1472. $:-\$

Simon_idnet · Sep 18, 2009, 22:29:50

Quote from: stevethegas on Sep 18, 2009, 15:19:15
Simon are you suggesting that this be universal setting for all idnet ISP users or is this more dependent on the router/computer combination?

1458 is the recommended MTU setting for ADSL Max in the UK. If your PC is set to a higher MTU setting then large packets will become fragmented which will impair performance.

1500 is the standard MTU setting for Gigabit links as that supports Jumbo Frames. Macs ship with NICs that support GigE by default. Macs are pretty good at detecting the MTU setting of devices further upstream and will adjust themselves accordingly. However, a wireless link can cause that detection to go faulty which I why I'd recommend setting the MTU size manually. Windows habitually gets most of this stuff wrong so it's probably best to set everything manually (though Microsoft is getting steadily better at that).
S

Simon_idnet · Sep 18, 2009, 22:35:38

Quote from: stevethegas on Sep 18, 2009, 22:20:56
I think I'll leave the Macbook wireless on auto for MTU as I don't seem to have any issues. Still puzzled by simon_idnet comment to set router at 1458 as posted in the other thread I thought it was 1500 for idnet. Certainly on my Windows machines were not seeing any packet loss with 1472. $:-\$

Hi Steve

Try setting your router to 1458 and your PC to the same (or 1450) to see if it makes any difference. Which version of Windows are you running? If might have detected that 1472 is higher than the achievable maximum and has automatically stepped-down (treating 1472 as a ceiling rather than a hard setting).
S

Steve · Sep 18, 2009, 22:42:57

Thanks for the informative replies Simon,I will do as suggested although I didn't think I had any issues. The Windows machines are Vista with TCP/IP on Auto

Sebby · Sep 19, 2009, 00:00:42

Quote from: robbo1 on Sep 18, 2009, 19:37:21
The very first website I went to (facebook) took an age to log into. So I changed MTU back to 1500 and it logged in instantly. Then I tried to post back here, and with 1500 it wouldn't get this the idnetters website. I changed it back to 1458 and it logged in here instantly.

I am very confused.

Could it be a problem with my router.

I have been trying to convince the wife that i should get a wireless N router.. (Please let it me the router, please let it be the router)

I reckon those results were just coincidence, rather than the 2 sites liking different MTUs.

robbo1 · Sep 22, 2009, 19:55:31

Well I thought I would reply back.

I have now had my MTU set to 1458 for about 3 days now and I am finding the loading of web pages much better.

I have to say that my average download speed seems to have slowed slightly by about 1 Mb/s but it is very difficult to judge consistently.

I am still left a little confused by the whole MTU thing, but if it aint broke, don't fix it!!

Thanks all

Robbo

Sebby · Sep 22, 2009, 20:03:02

Fingers crossed things remain like this.

Rik · Sep 23, 2009, 09:37:14

Let us know if you want us to talk you through the MTU concept, Robbo.

robbo1 · Oct 08, 2009, 19:23:01

Well, I suppose it has been about 3 weeks since my last post, and I have to admit that although things are slightly improved, there are still problems.

An ideal example is with BBC Iplayer streaming (as apposed to the download method). Very often (probably every other time I try to watch something), the BBC intro seems to play, but then the actual programme itself doesn't load (with the little circle thing just going round and round for ages). Sometimes, if I fully quit Safari (on the MacBook) it will then work, but the only way to guarantee that it will work is to re-boot my router.

I have found that if I set my MacBook MTU to manual, next time I check it, it seems to have set itself back to Automatic, so I am not sure if this is a factor?

I also have an XP SP3 running MediaPortal as a Media Centre PC (if you haven't tried MediaPortal you should by the way, it rocks), and that also seems to suffer from similar problems, but since I hardly ever use it to access the internet (only for recording TV and watching films etc via my TV), it is difficult to be sure if the problems are the same.

When I transferred to IDNET I came from Orange, and I am using my old 3COM router which has not been used for ages (as I was using the supplied LiveBox), so it is very difficult to say if it is the ISP change or the hardware change (never had this problem on Orange, albeit the downloads were far far slower).

If people think a router change may help, can anyone suggest a good (CHEAP) router, which is wireless N and 10/100/1000?

Thanks all

Robbo1