I'm trying to split the cable going into my internet modem so I can use it for a TV also. I saw this splitter at Home Depot and I'm wondering if it works well? IDEAL 2 Way Digital Cable TV Splitter (Model: 85-132 | Internet/Cat: 941322 | Store SKU: 1000449513) $3.98
Shaw provides free splitters - go to one of their outlets and they'll supply the proper one - 5-1000MHz minimum and two way. With a modem you should not have a splitter on that line as the modem should be the first split coming into your home. You might get away with it, but then again you might have problems. Call Shaw and have them do it properly.
I have 2 splitters on my cable modem line. A 2 way in the living room where my main TV is and a 3 way in my "office", where I've got my cable modem, phone terminal and another TV (actually computer monitor) connection. All splitters and cables were installed by Rogers and everything leading to the cable modem has a red tag on it. I also have a 2nd feed in my bedroom, which serves only a TV.
When the service provider does the installation they have special splitters that they can use that have specific losses per side/leg of the splitter. As stated, get Shaw to do this for you - they'll use the correct equipment and check the signals.
JamesK, what works for you may not work for someone else.