Hamburg, Germany  - It sounds great: lightning quick surfing at up to 16 megabits per second. The reality, though, is often somewhat different. The transmission rates claimed by Internet service providers are rarely achieved in practice. In some cases it is the equipment being used on the customer side that's to blame - not to mention the settings on the computer and router.

Roughly one in five calls to the call centre of DSL (digital subscriber line) provider Hansenet is related to the speed of the Internet access, says Markus Leptien, director of the company's application development department in Hamburg. "We can then check fairly quickly whether there's a problem with the line," the engineer explains.

Yet in many cases the real problem is just a misunderstanding of what DSL really is. When DSL providers speak of 16 megabits per second (Mbit/s), they are referring to the downloading of data from from the Internet - and not uploading of files or large e-mail messages. "Many users are confused by that," Leptien says. The upstream tempo is typically no more than 1 MBit/s.

Yet the Internet providers are not quite innocent when it comes to another misunderstanding. It has taken many of them until only recently to add the prefix "up to" when touting their speeds, since the figures are solely the maximum theoretical speeds. Hansenet informs its customers about the actual maximum achievable transfer rates for a given connection.

Once the misunderstandings have been cleared up, users should then check their own equipment: The first step is to update the firmware on the router, Hamburg-based Computer Bild magazine (9/2008 issue) recommends. For those using a WLAN router, checking the location is the next step.

It's simple to check the reception quality within Windows. A symbol showing the strength of the signal being received by the computer is shown in the task bar. It is often helpful to turn the router or its antenna a bit. One source of disruptions can come if the router is placed directly near the base station for a cordless telephone.

Multi-family houses in particular are susceptible to situations where the various WLAN nets slow each other down. Markus Leptien therefore recommends switching the transmission channel on the router. This can be done using the PC's browser - simply set a password and then configurations can be made. Many devices also offer to option of transmitting on the 5 gigahertz (GHz) network instead of the 2.4 GHz one. That represents one way around the data traffic jam. The WLAN module on the computer must support the 5 GHz WLAN mode for it to work.

It's simple to determine whether the WLAN is to blame for any speed problems at all, says Ralf Sauerzapf, a spokesman from T-Home in Bonn: "Simply try accessing the Internet using Ethernet," he says. Another potential cause of slow DSL can be a defective or outdated splitter, the device that separates voice and Internet data from one another. The splitter can also be replaced quite easily.

Markus Leptien also points out that Windows systems earlier than XP with Service Pack 2 do not support more than 6 MBit/s in their default settings. The corresponding settings in the system can be undertaken with just a few mouse clicks using Dr TCP, a utility program available for free on the Internet.

For those who have had a DSL connection for a long time without ever switching modems should check whether the device supports ADSL2+, Computer Bild recommends. That standard ensures that the device can handle DSL at up to 16 MBit/s. The older ADSL2 standard only supports up to 8 MBit/s.

It also helps to lower the MTU value in the router. MTU stands for Maximum Transmission Unit and describes the maximum size of the data packets that can be sent in the network. Leptien recommends setting the value to 1492. If the MTU value cannot be set via the router, then Dr TCP can help instead.

INFO BOX: One Firewall is Enough. Anyone who uses a router to get on the Internet doesn't need another firewall on their computer, says Markus Leptien from the online service provider Hansenet. A second firewall in this case offers no additional security, and only serves to slow the computer and by extension surfing. The same applies for virus scanners: "One is enough," Leptien says. (dpa)