Lancom 1811 User Manual

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Lancom 1811 User Manual Manual pdf 82 page image

LANCOM 1811 Wireless DSL – LANCOM 1821+ Wireless ADSL Chapter 10: Troubleshooting82ENIncreasing the TCP/IP window size under WindowsIf the actual transfer rate of a DSL connection is significantly below the fastestrate listed by the provider, there are only a few possible causes (apart from theabove-mentioned external factors) which may involve one's own equipment.One common problem occurs when large amounts of data are sent and recei-ved simultaneously with a Windows PC using an asynchronous connection.This can cause a severe decrease in download speed. The cause of this pro-blem is what is known as the TCP/IP receive window size of the Windows ope-rating system that is set to a value too small for asynchronous connections.Instructions on how to increase the Windows size can be found in the Know-ledge Base of the support section of the LANCOM web site (www.lancom.eu).10.3 Unwanted connections under Windows XPWindows XP computers attempt to compare their clocks with a timeserver onthe Internet at start-up. This is why when a Windows XP in the WLAN isstarted, a connection to the Internet is established by the LANCOM.To resolve this issue, you can turn off the automatic time synchronization onthe Windows XP computers under Right mouse click on the time of day Properties Internet time.10.4 Cable testingA cabling defect might have occurred, if no data is transmitted over LAN orWAN connection, although the configuration of the devices does not showany discernible errors.You can test the cabling with the built-in cable tester of your LANCOM.Change under WEBconfig to menu item Expert configuration Status LAN statistics Cable test. Enter here the name of the interface to be