If you are experiencing slow/erratic speeds, constant disconnects, or receive a "Can not obtain IP address from the server" or "PPPoE negotiation fail" errors when using a Linksys router it may be the MTU setting. Some Linksys models have an "Auto" MTU capability that does not function correctly and you must enable the "Manual MTU" function and manually enter 1492 (or less). To isolate whether the Linksys is causing the issue you should remove the it from the network and retest after connecting your computer directly the the modem.

Very Important Notes:
•Due to some operational issues it is VERY important that you have the latest firmware on your Linksys router. Please to the Linksys Download Website and ensure you have the newest firmware.
•When you set your MTU you must make sure the MTU is identical on all PC NICs and your router.
•The preferred method of utilizing a Linksys router in conjunction with another DSL Modem/Router is to configure the DSL Modem/Router for "bridged ethernet" mode and let the Linksys handle the PPPoE connection and higher routing functions.

Step 1
Important note: The following screen shots are based on a Linksys BEFSR41v.2 router and your screen shots may be different, however the steps and configurations are the same. Open a browser session and enter "192.168.1.1" in the address field to access the Linksys Interface. At the Username and Password prompt enter "admin" (without quotes) in the Password Field.



Step 2
Click on the Advanced tab from the menu.



Step 3
Select the Filters tab and find MTU. Select "Enable" or "Manual" (depending on model) and enter your MTU in the text field. Click Apply. The router will restart with the new settings. Two common model menus (BEFSR41 and WRT54G) and are shown below. Remember, your menu may be slightly different, but the overall process is the same. Do not leave it on Auto (even if 1492 is shown in the number field).

BEFSR41 Menu Example


WRT54G Menu Example


Step 4
When you receive the confirmation pop-up click on Continue.



Andy Houtz