My nest thermostat requires a mac filter . is there any way to add it to the MTAmodel TC8717T router
Yes, you can. Read the manual, p. 36:
What is your intent? Do you want you Nest Thermostat to always be assigned the same IP address? If this is what you want to do, then see p. 63
nope. The 8717 should be in bridge mode for an external router. TWC did allow router access, last sept spectrum disabled it, change settings back to whatever they felt like . use your router for NAT not theirs, you need to call them to turn off the 8717 wireless and bridge it as well.