If the DSL connection speed is lower than expected, here are some methods you can try to improve the connection speed.
We provide different modem code to avoid interoperability issues. Please go to WAN >> General Setup and use an alternative modem code to see if the line speed will improve. There are firmware files with different modem codes at Downloads, too. You may contact our local support for the appropriate modem code to use for your area.
For ADSL connection, you can set the modulation type at WAN >> Internet Access >> Details Page. It is set to Multimode by default so that DSLAM can use the type it prefers. However, you can try other modulation types to see if it can synchronize with a better speed. If there is another router that can get a higher speed with the same ADSL line, you may check its Modulation type for reference.
Transmitting more data at one time should be more efficient; however, larger packets will occupy the link for a longer time and will result in greater delays. Therefore, sometimes, slightly lower the MTU might bring out better connection speed. MTU can be set at WAN >> Internet Access>> Details Page.
With QoS enabled, some of the bandwidth will be reserved for particular Internet services and might result in a lower connection speed for your data. And there is Bandwidth Limit feature allows you to set a limitation of the transmitting/receiving speed. If your connection speed is lower than expected, please disable these features in Bandwidth Management and see if this could be the reason.
If none of above improve the connection speed, please check the SNR and Loop Attenuation in Online Status >> Physical Connection. These two factors are the indication of the line quality. If the SNR is too low(<6) or Loop Attenuation is too high(>40), then poor line quality might be the reason why the line speed is low, please consult your ISP about this.
If the low speed is not caused by poor line quality, please telnet into your router and enter these two commands "adsl status” and “adsl optn status”. Then copy the information and send it to our Technical Support for further investigation.