Does the system sometimes "forget" its mtu settings?

When I first boot the system, I enter a command to set the maximum
transmission unit for external traffic as follows:

ip route change default via 10.0.0.1 mtu lock 1412

(Here 10.0.0.1 is my router)

I have recently upgraded my Debian system, and I have noticed that I am
getting a of network problems.

Could there be some network event (such as a network error, or network reset
request within an application program) that is causing the system to forget
that the mtu for external traffic is 1412?

Mark.

--
Mark Hobley
Linux User: #370818 http://markhobley.yi.org/