do you use a wireless router on your own attached to your cable modem?
I have a Linksys router my self and everything works all right
I believe You should check your Touchstone Status on your own:
http://192.168.100.1/phy.htmand see the values of SNR/DB which means the signal loss e.c.t
If you get smaller values that this:
Downstream
Freq/Power: 700.000 MHz 6 dBmV
Signal to Noise Ratio: 35 dB
Modulation: QAM256
Upstream
Freq/Power: 36.000 MHz 45 dBmV
Channel Type: DOCSIS 2.0 (ATDMA)
Symbol Rate: 5120 kSym/sec
Contact cablenet and told them to install an amplifier on your premises.
I have an amplifier/splitter (box) installed on my rooftop but is not in use (turned off the signal comes pass-thru) since i got good signal. Cable guys told me if any other resident of my building want cablenet (currently i am the only subscriber in the building) they would use the amplifier/splitter in order to split the one cable into 2 and more.