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Appendix A: Troubleshooting
Common Problems and Solutions
Dual-Band Wireless Access Point
VPNs that use IPSec with the ESP (Encapsulation Security Payload known as protocol 50) authentication will work
fine. At least one IPSec session will work through the Router; however, simultaneous IPSec sessions may be
possible, depending on the specifics of your VPNs.
VPNs that use IPSec and AH (Authentication Header known as protocol 51) are incompatible with the Router. AH
has limitations due to occasional incompatibility with the NAT standard.
Change the IP address for the Router to another subnet to avoid a conflict between the VPN IP address and your
local IP address. For example, if your VPN server assigns an IP address 192.168.1.X (X is a number from 1 to 254)
and your local LAN IP address is 192.168.1.X (X is the same number used in the VPN IP address), the Router will
have difficulties routing information to the right location. If you change the Router’s IP address to 192.168.2.1,
that should solve the problem. Change the Router’s IP address through the Setup tab
of the web interface. If you assigned a static IP address to any computer or network device on the network, you
need to change its IP address accordingly to 192.168.2.Y (Y being any number from 1 to 254). Note that each IP
address must be unique within the network.
Your VPN may require port 500/UDP packets to be passed to the computer that is connecting to the IPSec server.
Refer to “Problem #7, I need to set up online game hosting or use other Internet applications” for details.
Check the Linksys website for more information at www.linksys.com.
6. I need to set up a server behind my Router and make it available to the public.
To use a server like a web, ftp, or mail server, you need to know the respective port numbers they are using. For
example, port 80 (HTTP) is used for web; port 21 (FTP) is used for FTP, and port 25 (SMTP outgoing) and port 110
(POP3 incoming) are used for the mail server. You can get more information by viewing the documentation
provided with the server you installed. Follow these steps to set up port forwarding through the Router’s web-
based utility. We will be setting up web, ftp, and mail servers.
A.Access the Router’s web-based utility by going to http://192.168.1.1 or the IP address of the Router. Go to the
Advanced => Port Forwarding tab.
B.Enter any name you want to use for the Customized Application.
C.Enter the External Port range of the service you are using. For example, if you have a web server, you would
enter the range 80 to 80.
D.Check the protocol you will be using, TCP and/or UDP.
E.Enter the IP address of the PC or network device that you want the port server to go to. For example, if the web
server’s Ethernet adapter IP address is 192.168.1.100, you would enter 100 in the field provided. Check
“Appendix D: Finding the MAC Address and IP Address for Your Ethernet Adapter” for details on getting an IP
address.
F.Check the Enable option for the port services you want to use. Consider the example below:
