There are a few things you need to do -
1) the cable modem needs to have route back to your 10.10.17.0/24 subnet so if it doesn't have one you need to add a route on the modem pointing back to the 3750
2) you need will need to setup NAT for the 10.10.17.0/24 subnet on the cable modem
However some cable modems will not allow you to do either (I have no experience of the modem you are using).
Adding a route should be easier but often modems such as this will not allow it.
In addition some cable modems will only NAT for the directly connected IP subnet ie. the one used between the 3750 and itself.
Your 10.10.17.0/24 is not directly connected.
So I'm not saying it won't allow you to do these things but it might well not.
If you can't then if you had a router instead of a L3 switch there is an easy solution because routers do NAT but virtually all L3 switches don't and yours doesn't.
So your only way of getting this to work with the L3 switch is put all your devices in a common vlan ie. the end devices and the connection to the cable modem are all in the same vlan.
But first see what the cable modem can do.
Jon
