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LANCOM 821 ADSL/ISDN – LANCOM 1621 ADSL/ISDN – LANCOM 1711 VPN

Chapter 9: Troubleshooting

Numerous other factors involving the Internet itself can also influence the transfer rate.

Increasing the TCP/IP window size under Windows

If the actual transfer rate of a DSL connection is significantly below the fastest rate listed by the provider, there are only a few possible causes (apart from the above-mentioned external factors) which may involve one's own equipment.

One common problem occurs when large amounts of data are sent and received simultaneously with a Windows PC using an asynchronous connec- tion. This can cause a severe decrease in download speed. The cause of this problem is what is known as the TCP/IP receive window size of the Windows operating system that is set to a value too small for asynchronous connec- tions.

Instructions on how to increase the Windows size can be found in the Knowl- edge Base of the support section of the LANCOM web site (www.lancom.de).

9.3Unwanted connections under Windows XP

Windows XP computers attempt to compare their clocks with a timeserver on the Internet at start-up. This is why when a Windows XP in the WLAN is started, a connection to the Internet is established by the LANCOM.

To resolve this issue, you can turn off the automatic time synchronization on the Windows XP computers under Right mouse click on the time of day Properties Internet time.

9.4Cable testing

LANCOM1711VPN only

A cabling defect might have occurred, if no data is transmitted over LAN or WAN connection, although the configuration of the devices does not show any 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

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Lancom Systems 821 Unwanted connections under Windows XP, Cable testing, Increasing the TCP/IP window size under Windows

1621, 1711, 821 specifications

Lancom Systems is a notable player in the networking solutions market, and its range of routers, specifically the 821, 1621, and 1711 models, showcases the company's commitment to delivering robust, high-quality products for various enterprise needs. Each model brings distinct features, making them suitable for different environments and operational demands.

The Lancom 821 is particularly designed for small to medium-sized enterprises (SMEs) requiring reliable internet connectivity and secure networking. This router supports various VPN technologies, ensuring secure data transmission across the organization. Equipped with advanced firewall capabilities, the 821 can handle multiple connections while protecting against potential cyber threats. Its support for IPv6 enhances compatibility with future networks, making it a long-term investment. The device’s manageable architecture allows for remote access and troubleshooting, reducing the need for on-site IT interventions.

On the other hand, the Lancom 1621 is tailored for larger organizations or those with more extensive networking demands. This model offers enhanced throughput and is capable of managing large volumes of traffic without compromising performance. It features a variety of WAN connection options, including DSL, LTE, and fiber, allowing businesses to choose the best solution for their requirements. The 1621 also incorporates sophisticated Quality of Service (QoS) settings, which prioritize critical applications to ensure optimal performance during peak times. Built-in redundancy features enhance reliability, making it an excellent choice for mission-critical applications.

The Lancom 1711 takes networking capabilities a step further, targeting enterprises with even more complex needs. It boasts advanced routing and switching features, making it suitable for enterprise-grade deployments. The 1711 supports enterprise WLAN management, allowing seamless integration with wireless access points. Its robust performance over WAN connections enables the deployment of various real-time applications, such as voice over IP (VoIP) and video conferencing, without latency issues. Security is a top priority, with features including an IPSec VPN and integrated threat detection to safeguard organizational data.

In summary, the Lancom 821, 1621, and 1711 routers serve as versatile tools for businesses, each designed with distinct capabilities to meet specific networking needs. Their strengths lie in their security features, support for various connection types, and reliable performance under heavy loads. With these devices, organizations can ensure that their network infrastructure not only meets current demands but is also poised for future growth.