I'm a little confused. I guess that could be a general statement but let me elaborate.
I have a Cisco 887VA router that I want to use for our home Internet connection. (Telecom VDSL)
I have been using the supplied router from Telecom but decided it was about time I setup the Cisco properly.
According to the Telecom website, the MTU should be set to "1500 or auto"
As such, I didn't change the mtu size in the config.
I ran some ping tests to check and it seems that it was set correctly at 1500.
However, various sites were slow and some simply timed out. As an example I could (eventually) get to www.telecom.co.nz but trying to log into "mytelecom" timed out.
Also www.speedtest.net timed out on me.
Adding the following lines into my config under the Dialer interface fixed this up:
ip tcp adjust-mss 1452
It's all working so that all well and good. I'd just like to know *why* it's working. :)
I understand that typically a PPPOE connection requires a 1492 size MTU but then, why does Telecom advise in the VDSL settings to use 1500?
And when using 1500 it just doesn't work properly.
Or is my understanding of this simply ... flawed?
Thanks for any insights on this.