Moca and internet

Can I add a moca adapter to cox service that only has internet? I currectly am using their phone/cable modem by Cisco DPQ3212 and Netgear R6400 wireless router. I dropped the cable and phone service.  I have coax outlets thru out my 2 story house but have weak wfi signals everywhere. Was hoping by adding the adapter I could use a direct wired ethernet to Roku for better streaming.

Any help appreciated.