AT&T Fibre 1000 and MOCA Extenders

Need way to extend Wi-Fi through lathe and plaster constructed home. Can MOCA extenterd be used with AT&T provided Pace 5268AC gateway/router?

The Coax port of the 5268 is intended to support HPNA, or MOCA.  Purchase an adapter you can return and give it a shot.

Currently, there is one of my TVs on that COAX port. Can a MOCA rated COAX splitter be used to allow that TV to still be available for viewing AND MOCA Wi-Fi possible at the same time?

A 1000+ MHz (i.e. "MOCA rated") splitter with no unterminated ends should allow you to extend your HPNA network.  However, MOCA and HPNA are not actually the same thing.  They are two different protocols that can operate over the same medium (well, HPNA can work on a whole lot of mediums, but coax is one of them).  You would have to get an HPNA to Ethernet adapter to connect a Wi-Fi Access Point to speak directly to the Gateway.  

To use MOCA, you'd need two adapters one for each end (because the 5268 doesn't use the MOCA protocols), and I'm somewhat doubtful the two protocols could coexist on one cable.

Keep in mind that the HPNA network is bandwidth limited.  If you use too much of it with your new network clients it may adversely affect your TV reception.

You might want to consider Ethernet bridges that use your Electrical Power wiring.

Would an Ethernet-to-MoCA adapter connected to one of the Pace 5268AC ethernet ports be a solution? Then a MoCA Wi-Fi access point at the other end of the COAX cable?

That's what I'm thinking, yes.

Thanks.

Are there any recomendations for an Ethernet-to-MoCA adapter and a MoCA Wi-Fi access point?

NO recomendations for an Ethernet-to-MoCA adapter and a MoCA Wi-Fi access point!! Is there ay help/guidance as to what devices may help resolve this issue?