cant change wan mtu on technicolor router

[#1]

when i telnet into router and try to change wan mtu i get error.says changes wont be saved on dynamic ip.i can change local but not wan

[#2]

Have you checked with:
ip iflist
The MTU may have changed despite the error.

[#3]

yea i checked after m8 still didnt work.

[#4]

The following works for me, get the error but the mtu still changes.
ip ifconfig intf=Internet mtu=????
saveall
Alternatively you could try:
ppp ifdetach intf=Internet
ppp ifconfig intf=Internet mru=????
ppp ifattach intf=Internet
saveall
If you use this second one, I would make sure the setting is the same in the ip section.

[#5]

the top 1 worked thanks for your help m8