My problem is I can login to guest act using no password

"Hi,

Have you checked that you have the latest firmware installed. On the Linksys website V2.2 and V2 model routers had a firmware update dated 16.1.2015 which ""addressed various security vulnerabilities"" (-not detailed what). Your problem may be linked to this if you have an earlier version of the firmware. Apparently V1 models were not affected because they didn't get the firmware update.

Here is a link to the relevant page for the firmware.

http://www.linksys.com/au/support-articl...

Here is a link to the relevant page on how to update your firmware.

http://www.linksys.com/au/support-articl...

Be sure to write down or save all your router settings that you have made. A firmware update will restore your router to factory defaults."