That won't work. You need to keep the 2 (Internet & HyppTV) networks separate physically by using either 2 cables or 2 sets of homeplugs.
Alternatively you can trunk both internet & hypptv vlans onto 1 set of homeplugs (or 1 cable) but this will require a vlan capable router/switch on one end and a vlan aware switch on the other. This is what I do in my house. I'll see if I have time to do a diagram.

This is a simplified version of what's in my house.
The red pipe for the VLAN Trunk can be:
1. One ethernet cable which is what I use or
2. A pair of Homeplugs or
3. Even a wifi bridge if you like.
VLAN 50 is my main LAN traffic. I also have other VLANs which is not illustrated to keep things simple.
you mentioned vlan capable router. Is the AC-68U capable of doing that?