Fibre Hub MTU settings

[MHC]

On looking into the 2701HGV-C settings I find that it defaults to an MTU setting of 1492 which slightly lower than that normally used - 1500.   

What is the reason for the lower setting and will changing it to 1500 cause any issues?

[a-hill]

MTU is Maximum Transmission Unit and determines the max size of packet that will be sent over the network. BT Wholesale determined that the best MTU settings for their ipsteam DSL connections are 1458 to 1500. We've seen some occasions where 1500 is slightly too much for some lines (on very rare occasions mind you). You shouldn't really get any adverse effects changing to 1500, but then you won't really get any gains either.

[MHC]

I know what MTU is and what it does but cannot understand why the default is set below the standard setting.

I have had Infinity installed for a week and am finding several niggly little issues and problems that have appeared - and were NOT present with my ADSL2+ service.

For example;  some web pages NEVER finish loading and just sit there,   distinct lag when accessing some sites,   possible rstrictions on use of port 80 for downloads,  the upload speed seems to be fixed 20% below the agreed, capped figure.

I want to check everything here to ensure my PCs and network are not the cause - unlikely, before I speak with tech support in detail.