OK Steve:
This is with no Adblocker or Firewall running, but going through the default Notts proxy server (which to me is very slow and causes slow browsing and time outs).
Code:
Pinging www.bbc.net.uk [212.58.224.126] with 2000 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Reply from 212.58.224.126: bytes=2000 time=281ms TTL=247
Request timed out.
Reply from 212.58.224.126: bytes=2000 time=214ms TTL=247
Reply from 212.58.224.126: bytes=2000 time=194ms TTL=247
Reply from 212.58.224.126: bytes=2000 time=130ms TTL=247
Reply from 212.58.224.126: bytes=2000 time=153ms TTL=247
Reply from 212.58.224.126: bytes=2000 time=166ms TTL=247
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 212.58.224.126: bytes=2000 time=137ms TTL=247
Reply from 212.58.224.126: bytes=2000 time=48ms TTL=247
Reply from 212.58.224.126: bytes=2000 time=107ms TTL=247
Request timed out.
Reply from 212.58.224.126: bytes=2000 time=175ms TTL=247
Ping statistics for 212.58.224.126:
Packets: Sent = 20, Received = 10, Lost = 10 (50% loss),
Approximate round trip times in milli-seconds:
Minimum = 48ms, Maximum = 281ms, Average = 160ms
May seem a silly question but I thought 1500 was the biggest packet size that ethernet uses? That's what WinXP's MTU is set to, so I did the same test with a packet size of 1500:
Code:
Pinging www.bbc.net.uk [212.58.224.82] with 1500 bytes of data:
Reply from 212.58.224.82: bytes=1500 time=176ms TTL=247
Request timed out.
Reply from 212.58.224.82: bytes=1500 time=107ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=163ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=154ms TTL=247
Request timed out.
Request timed out.
Reply from 212.58.224.82: bytes=1500 time=59ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=179ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=25ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=24ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=106ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=111ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=56ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=39ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=29ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=99ms TTL=247
Reply from 212.58.224.82: bytes=1500 time=130ms TTL=247
Request timed out.
Request timed out.
Ping statistics for 212.58.224.82:
Packets: Sent = 20, Received = 15, Lost = 5 (25% loss),
Approximate round trip times in milli-seconds:
Minimum = 24ms, Maximum = 179ms, Average = 97ms
Looks like pinging with lower values until one works 100% and use that as the MTU value?