I have two TalkTalk broadband lines. One, my wife's, has a SMC Barricade, the other, mine, has a Vigor 2800 as the ADSL Router. Both work perfectly except:

On the forums at www.forexfactory.com, I can call up the page to create a reply or a post, but if I try to preview it or post it, after a timeout period, I am looking at a blank page with the word 'Done' in the status bar. If I change the PC's gateway address to use my wife's router, this problem disappears and the posting is executed.

Seems to me the problem has to be in the Vigor. I have tried turning everything off (IM, p2p, DOS Defence, content filters), even the default Call Filter. Still cannot post to the Forum. In a minute, I will be finding out if this applies to this Forum too.

Does anyone have any idea what the router might be doing to block the communications after I click 'Submit' or 'Preview'?

Thanks.

Have you tried this ?

Yes - tried unchecking that box. No difference. This is a weird one that is peculiar to the forums on forexfactory.com As you can see, it doesn't stop me posting here. :?

Try dropping your MTU.

To check your MTU, telnet into your router then

Code:

WAN PPP_MSS ?

To change the setting

Code:

WAN PPP_MSS 1200 (or whatever)

I have seen values as lows as 1200 suggested. I'd check the setting first then change it to 1200. If that works, I'd increase it slowly and see what happens. If it does not work, I'm not sure what to do.

Thanks for the input, NJH. Spot on! I've reduced the MTU to 1200 and everything works.

If it would work at a slightly higher level, would I get any benefit from raising it ?

Thanks

Raising it would be marginally better. Every packet of data sent over the internet carries a few bytes of header information. The smaller the packet, the more packets need to be sent to carry the same amount of data, and each packet has its own overhead.

I suggested 1200 as it is quite a dramatic cut. You could try 1400 and see if it works. If you search the forums you will see a number of different values being suggested. Have a read of this and reset your MTU then use one of your problem sites as the target for the test. It may allow you to find your optimum size.