I saw your post in linksys forum and taking direct quote from zee29:
The guest access feature of the router is well for guests only. The purpose for this is to allow other people to connect to your wireless network but they do not have access to your local network (no access to your computers). This feature is available for wireless connection only and will be in the local network and not for accessing the router remotely.
If you would like other people to access your files or shared media then FTP will be the answer for that. You can set up or create shares that will have permissions like read only or you can setup read and write only.
For more information, you may also check the link below:
Title: »kb.linksys.com/Linksys/ukp.aspx? ··· e=search
Just to add, take a look at the link posted which explains in details.