Check and see if your router has any settings that allow you to change the MTU.
The MTU set in your router should never be below that of the devices on the local network (PCs) or it can cause the "black holing effect".
The other thing to check for - see if your router is blocking ICMP pings.
Go to somewhere like grc.com and run a security (stealth) check.
Although grc.com has some good advice the one thing that I any many others disagree with is that on grc.com you can fail his stealth check simply because your router hasnt blocked pings.
When you block pings, you turn off ICMP, which is a valid internet protocol and needed for path MTU discovery.. therefore a side effect of making your router unpingable is that it stops PMTU discovery working and the "internet breaks".
>> 1. Why is it necessary to change the MTU settings of every device that I connect to my router.
The correct packet size needs to be end to end point - your PC is the end point receiving the data, the server sending the data is the other end point. ie its the 2 devices that are communicating with each other.
>> Should the router manage the MTU packet size of the devices.
No - packets just flow through the router. On the internet packets will pass through many, many routers and switches, its the routers job to forward them to the correct destination.
A router firewall may block bad packets and protect your network, but it doesnt have anything to do with "wrapping" and "unwrapping" the data packets which are done at the end points.
>> Is it an issue with my ISP, but Orange are notorius at tech support.
Unfortunately this is an issue that does seem to affect a lot of orange users, so much so that orange problems asked permission to replicate my MTU pages for orange users :/
Its therefore likely that its one/some of Oranges' network routers have a low MTU setting which is the "blackhole".
>> do you know of any way of changing the MTU settings on a Sony PSP.
I dont.. I dont have a PSP, so not the best person to ask Im afraid. :/
What is happening is somewhere along the line data isnt getting back to your PC, the place where the packets are being dropped because they are too large is known as the blackhole.
So your PC is saying to a remote server send me info.
The server is going ok then - here you go and its sending packets at the default size of 1500.
Some-where on the path back to you theres a router which has an MTU set lower than 1500 therefore the packets are being dropped because theyre too big to pass through.
When you set the MTU on the local machine your PC says
Send me data but send the packets no bigger than xsize.
The remote server then wraps up the packets to send to you making sure that they are the size requested and not default.
Above version is simplified or I'd be here all night typing stuff out
.. and whilst I was typing all the above out - erics already beaten me to it and posted.. but Im still going to post anyhow
