Are you on Broadband?
Are you having problems logging into your webmail, Online Banking, or Secure Access sites?
Your problem could be sorted as quick as a flash.
If you are using a TalkTalk modem, then more likely you will have either a Smartax MT882 or a HG520 Wireless modem.
To get into the settings for this modem you need to open a web browser, and in the address bar type:
192.168.1.1
or
192.168.1.2 (for people using usb on the Smartax Modem)

For Smartax:
Click on Basic on the left hand margin.
Then Click WAN Settings.
Then Click on the Yellow Pencil icon under the Actions Column.
Scroll down to where it says Configured MTU and change the default value (1432) to 1300.
Click Submit at the bottom then on the left margin again click on Save All.
Click ok wait 10 seconds and reboot the modem.

For HG520:
Click on Basic on the left hand margin.
Then Click WAN Settings.
Scroll down to where it says TCP MSS and change the default value from 1400 to 0
Then the next field below (MTU) change from 0 to 1300.
Click Submit at the bottom.
Wait 10 seconds and reboot the modem.

If your using your own router then follow the instructions on where to find your MTU settings and change the value to 1300.
If all goes well you should be browsing your email and checking your bank account with ease.