There have been major issues regarding networking security these days, but specifically this one has emerged out to be the latest threat to networking security and it might have been affecting your DSL speed
and reduced it to its half as well. Its just like the ‘man in the middle’ address resolution.
Common Symptoms
1. Regular losses of router’s IP ping( this often
gets your net down).
2. Continuous data transfer speed lowering.
3. Unknown error messages.
4. Often errors while trying to log out of the ISP’s server or permanent logging
failure.
5. Broken downloads.
This problem cant be caught by your firewall, so it is suggested to contact your
ISP customer care or ask your network administrator (the personnel who installed
the net at your home) to resolve this problem and block the hackers.
Alternate causes can be network virus with in the sub-network area of the
router, so this is the soul responsibility of the network admin only
Posted by anant01 
anant01