Slow internet

[turner9000]

Hi,
I'm currently running a twin tuner cable box and have noticed that when both feeds are plugged into the box the Internet speed seems to drop, when, I unplug the along the speed returns, does this mean I need a signal booster?
Any advice would be appreciated.
Tom.

 

[alcable]

is your cable line for twin tuner box

 

[turner9000]

Yes a cable line.