My router is stuck at 802.11g, it won't use 802.11n

[#1]

Hi all
I've recently upgraded to 77mb fibre, from copper broadband.
An ethernet cable into the fibre modem gives me 72 mb,  but when I connect the supplied technicolour modem, but i can only get 22-28mb over wifi. While finding the best channel for my router, the wifi analyser noticed that my router is only running 802.11g not 802.11 n.
I've spoken with plusnet support and they werent any help, although they did agree to send me a new router, they didnt think that this would work. He mentioned something about telnetting into the router, but didnt really know what he was talking about.
has anyone else had/overcome this problem or have any suggestions?
thansk
matt

[#2]

http://npr.me.uk/telnet.html#wirelessn explains
However I assume that all the connected devices are wireless n enabled

[#3]

Silly question, but what device are you using to test with - Does it support 802.11n?
What kind of encryption are you using?

[#4]

I am using two laptops, which both support N. we have a few other devices, TV, tablets, 1st gen Ipad, printer and a couple of phones. I've not checked them all for type N.
can it only support either N or G at the same time?
and I use WEP encryption.

[#5]

WEP will be the reason then - You have to use WPA2 with 802.11n

[#6]

thanks I'll update it and let you know how it goes

[#7]

thanks
that has clicked it on to Type N and I've just clocked my broadband at 35 Mb over wifi. I'll try again next to my router.

I am a bit surprised tho, that my wifi network is the slow link in the chain.

matt