Can´t connect to certain sites

i doubt the router has anything to do with the problem. most likely culprit is a pop server (handles incomming email). check with your email provider to see if they changed servers...
have you made any changes to your router or firewall? i guess it could be a port that got closed that your email was using
eh, here is a usefull website shows server names and ports used
http://www.arclab.com/products/amlc/list-of-smtp-and-pop3-servers-mailserver-list.html

Are you able to use your wireless router with a PC or laptop for browsing the internet?

Ask COMCAST for the names of their POP-server and of their MAIL-server, and configure Outlook Express to use those names.

Microsoft Live Mail is "web-based" -- all you need to do is to web-surf to their web-site, login, and click "send/receive" or click "compose" and later "send".

Send problems. There are several common causes of problems with sending email:

• Mail queued. If you appear to be able to send email but it never arrives, it may be in a queue. Some applications put email in a queue when you send it, and the user has to manually send all queued mail to actually transmit it. Check your File and Edit menus for any queues, and also check the status of the email in the Out mailbox to see if it was actually sent -- if not, send it again.
  
  
• Send on check. This is a common problem -- many email servers are configured to use the password authentication involved with checking mail to allow the sending of mail, and therefore require clients to check for mail at the same time or just before sending mail. If you get an intermittent error message and can send at some times and not others, make sure the option "send on check" is enabled in your email settings. As a temporary fix, you can often solve the problem by manually checking for mail shortly (a few seconds or minutes) before sending mail. This problem can also produce the message "relaying not allowed" described below, for much the same reason.
  
  

• Relaying not allowed. Many Internet access providers require clients within their network to use their own servers for sending mail, as a policy intended to cut down on email spammers sending spam through other provider's servers. If you have more than one email address and can download mail without problems from a POP account with a different domain name than is used by your Internet access provider, but get the error "Relaying not allowed" when you try to send, then you probably need to set the outgoing SMTP server address to the mail server of your Internet service provider, instead of your email provider. Search your Internet network provider's home page or call technical assistance to obtain the address of their SMTP server, and enter it in your email client settings (first copy and save your existing server setting in case you need to set it back). This error message can also be produced by the "send on check" issue described in the bullet above.
  
  
• Server down. If you can do a successful connection check, and the above suggestions don't help, and a recipient continues to say that email sent from you does not arrive, and you are certain their address is spelled correctly, then one of the email servers between you and your destination is likely down. Blocked email is typically cached and sent when the missing server comes back up, usually within a few hours or days. If the problem persists and you can successfully send to other email addresses, then the email provider of your recipient is likely having a problem -- you should contact them by phone and ask them if they are getting email from anyone else, request they send an email to you, and if necessary suggest they do a connection check from their end to help diagnose the problem.

This is from this webpage.

http://www.livinginternet.com/e/et_connect.htm

Disable your Firewall/NAT service or open ports 25, 110 and 141

dlieb,

connect ur cable first,from ur laptop to ur router..then if it will function,unplug the cable then connect ur laptop to the router manually..

this doesnt make sense as you wouldn't be able to send or receive. If you ave an antivirus programme check it's not scanning your message then putting it in the outbox. If you have changed your service provider recently but kept your old e mail address then the smtp settings are incorrect in your email send settings and may also require server authentication, although your pop3 receiving account may not need to change.

The current firmware allows the maximum transmission unit to be changed if needed. If you are having a problem sending or receiving email, or connecting to secure sites such as eBay, banking sites, and Hotmail, we suggest lowering the MTU in increments of ten (Ex. 1492, 1482, 1472, etc). What is my MTU? - To find the proper MTU Size, you?ll have to do a special ping of the destination you?re trying to go to. A destination could be another computer, or a URL. Step 1 Click on Start and then click Run. Step 2 Windows 95, 98, and ME users type in command (Windows NT, 2000, and XP users type in cmd) and press Enter (or click OK). Step 3 Once the window opens, you?ll need to do a special ping. Use the following syntax: ping [url] [-f] [-l] [MTU value] Example: ping yahoo.com -f -l 1472 You should start at 1472 and work your way down by 10 each time. Once you get a reply, go up by 2 until you get a fragmented packet. Take that value and add 28 to the value to account for the various TCP/IP headers. For example, lets say that 1452 was the proper value, the actual MTU size would be 1480, which is the optimum for the network we?re working with (1452+28=1480). Once you find your MTU, you can now configure your router with the proper MTU size. Note: AOL DSL+ users must use MTU of 1400. To change the MTU rate follow the steps below: For the DI-514, DI-524, DI-604, DI-614+, DI-624, DI-754, DI-764, DI-774, and DI-784: Step 1 Open your browser, enter the IP address of your router (192.168.0.1) and click OK. Step 2 Enter your username (admin) and password (blank by default). Click OK to enter the web configuration page for the device. Step 3 Click on the Home tab and go to the WAN tab. Step 4 The default MTU is 1500, to change this enter the number in the MTU field and click the Apply button to save your settings. Step 5 Test your email. If changing the MTU does not resolve the problem, continue changing the MTU in increments of ten. Note: If you have the European version of the DI-604, this procedure will not work. If you do not have an MTU option, please upgrade your firmware.

The current firmware allows the maximum transmission unit to be changed if needed. If you are having a problem sending or receiving email, or connecting to secure sites such as eBay, banking sites, and Hotmail, we suggest lowering the MTU in increments of ten (Ex. 1492, 1482, 1472, etc). What is my MTU? - To find the proper MTU Size, you?ll have to do a special ping of the destination you?re trying to go to. A destination could be another computer, or a URL. Step 1 Click on Start and then click Run. Step 2 Windows 95, 98, and ME users type in command (Windows NT, 2000, and XP users type in cmd) and press Enter (or click OK). Step 3 Once the window opens, you?ll need to do a special ping. Use the following syntax: ping [url] [-f] [-l] [MTU value] Example: ping yahoo.com -f -l 1472 You should start at 1472 and work your way down by 10 each time. Once you get a reply, go up by 2 until you get a fragmented packet. Take that value and add 28 to the value to account for the various TCP/IP headers. For example, lets say that 1452 was the proper value, the actual MTU size would be 1480, which is the optimum for the network we?re working with (1452+28=1480). Once you find your MTU, you can now configure your router with the proper MTU size. Note: AOL DSL+ users must use MTU of 1400. To change the MTU rate follow the steps below: For the DI-514, DI-524, DI-604, DI-614+, DI-624, DI-754, DI-764, DI-774, and DI-784: Step 1 Open your browser, enter the IP address of your router (192.168.0.1) and click OK. Step 2 Enter your username (admin) and password (blank by default). Click OK to enter the web configuration page for the device. Step 3 Click on the Home tab and go to the WAN tab. Step 4 The default MTU is 1500, to change this enter the number in the MTU field and click the Apply button to save your settings. Step 5 Test your email. If changing the MTU does not resolve the problem, continue changing the MTU in increments of ten. Note: If you have the European version of the DI-604, this procedure will not work. If you do not have an MTU option, please upgrade your firmware.

The current firmware allows the maximum transmission unit to be changed if needed. If you are having a problem sending or receiving email, or connecting to secure sites such as eBay, banking sites, and Hotmail, we suggest lowering the MTU in increments of ten (Ex. 1492, 1482, 1472, etc). What is my MTU? - To find the proper MTU Size, you?ll have to do a special ping of the destination you?re trying to go to. A destination could be another computer, or a URL. Step 1 Click on Start and then click Run. Step 2 Windows 95, 98, and ME users type in command (Windows NT, 2000, and XP users type in cmd) and press Enter (or click OK). Step 3 Once the window opens, you?ll need to do a special ping. Use the following syntax: ping [url] [-f] [-l] [MTU value] Example: ping yahoo.com -f -l 1472 You should start at 1472 and work your way down by 10 each time. Once you get a reply, go up by 2 until you get a fragmented packet. Take that value and add 28 to the value to account for the various TCP/IP headers. For example, lets say that 1452 was the proper value, the actual MTU size would be 1480, which is the optimum for the network we?re working with (1452+28=1480). Once you find your MTU, you can now configure your router with the proper MTU size. Note: AOL DSL+ users must use MTU of 1400. To change the MTU rate follow the steps below: For the DI-514, DI-524, DI-604, DI-614+, DI-624, DI-754, DI-764, DI-774, and DI-784: Step 1 Open your browser, enter the IP address of your router (192.168.0.1) and click OK. Step 2 Enter your username (admin) and password (blank by default). Click OK to enter the web configuration page for the device. Step 3 Click on the Home tab and go to the WAN tab. Step 4 The default MTU is 1500, to change this enter the number in the MTU field and click the Apply button to save your settings. Step 5 Test your email. If changing the MTU does not resolve the problem, continue changing the MTU in increments of ten. Note: If you have the European version of the DI-604, this procedure will not work. If you do not have an MTU option, please upgrade your firmware.