Problem logging in from mobile

This is my forum : http://www.cwforums.net

A lot of the users there access the site from their mobiles. But recently they are encountering problems logging into the site.
Please check this and inform me as soon as you can.
Thanks in advance.

What problem certain? Do they recieve a message or an error when is trying to log in?

Hello,

Please note that members cannot log in using the mobile version of the forum. They will need to switch to the classic version by clicking on the button at the bottom of the forum index. This should then allow them full access to the forum.

If this is not your problem, then please explain further. Thanks!

They are using the classic version only.
But when they try to log in the following error appears :

" Server not found "

I tried it on my phone & did not face any problem.

Could you log in ?

No they are using different phones.

ok I will ask them