Technically you can use the same wire as a middle bus for both the internet signal and your TV antenna, they use different carrier frequencies. However to keep them well separated you may need to use a modulator splitter on both ends.
See here:
B(ridge) and T(unnel) Crowd: Can You Run OTA Antenna TV and Internet Feeds on the Same Coax Cable? Yes!
that said - if you just have the one modem, it's going to be easier to just find the line going to the modem, and disconnect it from from that block and direct-connect it to the line coming in from the cable company (as Shawn said, probably the far left), so those 2 are now independent of the block. Then connect your antenna line coming into that spot on the far left instead. that will give you antenna access in any room.