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MTU Settings for Firewall Routers
When using Firewall Routers LAN-side of Sharedband, you will need to adjust the MTU Value of the WAN Connection that is connected to the Sharedband Routers, this is because Sharedband uses a 32 byte header that your Firewall Router doesn't account for. The principles within this article can also be applied to other Routers or Servers used on the Sharedband connection for uses such as VPNs.

In the UK a normal MTU on a standard ADSL line is 1492. However with some providers (such as Talk Talk) and connectivity technologies (such as Fibre/FTTC) this may be different. The MTU must be set equally on all Sharedband routers and so if mixing providers, please default to use the lowest MTU given. The MTU set on your Sharedband Routers can be found and adjusted by logging into them on the LAN and looking at either Network Settings or WAN Settings.

The MTU on your Firewall Router's WAN interface must be adjusted to a value 32 bytes lower than that set on the Sharedband routers. Examples of this simple subtraction are:

Sharedband Routers MTUFirewall WAN / VPN MTU
1492 1460
1432 1400

We provide instructions for amending the MTU on some 3rd party firewalls at

If you have any problems with MTU Settings please Raise A Ticket