The SNR on your ADSL line in some cases can be improved:
Negotiate a sync speed at the best time of day
Interference levels from electrical appliances is at its lowest during the early morning, around 5am. Rebooting your router at this time and negotiating a sync speed at this time could give you a better a sync speed.
Install a XTE-2005 Master Faceplate
If the master socket in your home has 1 outlet and ADSL filters are used a XTE-2005 Master Faceplate can be used instead of ADSL filters and the SNR will be reduced. These cost around £10 in the UK.
Use a different router
In relation to handling low SNR-lines not all routers are the same. There is no official data and success can be a case of trial-and-error. Most Speed touch routers have a good reputation on low-SNR lines.