I had a simular problem with my cable modem where it would go out for hours on end. After calling the cable provider (comcast) and after several diagonstic steps they sent someone out who replaced my modem. That worked for about a month. I also bought a radio shack splitter which worked for a while then would go out whenever it felt like. After I was told all of my cable wiring needed to be replaced (the wiring was only 8 months old) I added a signal booster from motorola and never had a problem since. This is not a splitetr. The cable goes in and a connection goes out. This unit can be installed before the soplitter or after. I bought mine at Best Buy.
By the way I was told from comcast that most of radio shacks items are poorly made and may hurt your signal not help it. I don't know if it is true or not.
Hope this helps
My high speed internet connection is provided by a large New York based cable tv provider. I loose my internet connection numerous times a day often while in the middle of important work.
Setup: My internet connection and tv signal come in over one line; I split the signal, as instructed by the cable company, through a splitter; the signal travels over CATV cable to a Surfboard SB4100 cable modem about 80 feet away, then via RJ45 network cable to a Linksys Ethernet Cable/DSL hub and then to the computers over RJ45. In the past each time I lost the connection I called the cable company; followed their lengthy automated diagnostic procedures (15 to 20 minutes) then spoken with a technican who wants me to redo all the procedures I just completed and then assures me it is not their fault so it must be something within my house which they would be happy to charge me for to diagnose the problem. They always say it is the splitter. Several months ago I replaced the splitter with a powered (Raido Shack) splitter to boost the signals that go to the tv's and the cable modem. This provided me with an uninterrupted connection for about 3 months. Recently the connection has started to fail again; it will sometimes reestablish a connection on its own; other times I have to go to the splitter, disconnect the internet connection and switch it with anyone of the three tv connections. When this is done I usually have to reset the cable modem after which I will have my internet connection back for an indeterminate period of time. Sometimes an hour sometimes a day.
Since I have run all new cable, bought all kinds of new splitters what else could be causing my continuing disruption in cable service. My tv service is never disrupted during these outages.

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