I seem to be having a similar problem. I lose my internet at the modem, while my HDTV is working fine in the next room. Power cycling the modem and router seems to have no effect. I generally can get it back up my going into the attic and reconnecting cable connections. There is a Surge Gap Drop Amplifier up there that was installed by Time Warner many years ago. At times power cycling it does the trick. I'm wondering about it going out. That being said; my modem is a
Motorola 5101u
Downstream
S/N ratio 37.6
Frequency 62,700000 Hz
Power -10.6dBmv
Upstream
Chanel ID 5
Frequency 36,1000,000 Hz
Power55.2 dBmv
Now wondering if I can solve the problem by swapping the Modem out. This is not the time of year to be in the attic in these parts.