Is there a way to place a Switch right after Fibr-Ethernet and before it reaches the ATT router?

Fiber setup is fiber to ont, Ethernet to red port on gateway. All outbound connections from yellow Ethernet ports on gateway. Either connect the wireless stb via Ethernet to the gateway or wireless stb to managed switch to gateway. Dvr and stb’s need to be on a separate network from data connections or run through a managed switch that separates iptv and data. Do you have any open ports on the gateway? My old setup had cat5 from the gateway to a managed switch. Wireless stb connected to a managed switch. Apple TV, pc, avr and ps3 also connected to the switch. I never had any problems. In current setup, tech ran a separate cat5 to the same location but now has the dvr there. 2 wireless stb’s in the house using the WAP. 

After reading your post again, where is the dvr? Are you saying the ont is downstairs and the gateway is upstairs? 

yes the ONT is downstairs and the gateway is upstairs same as the DVR.  

Basically downstairs is only one ethernet port in the room and that port is taken by the red cable from the ONT which then leads to the upstairs ports...there the router is connected to managed switches.  

What I am trying to do is somehow split the downstairs connection that comes right out of the ONT so I can use the ethernet to provide the direct port to the cable boxes.  

What I am trying to do is somehow split the downstairs connection that comes right out of the ONT so I can use the ethernet to provide the direct port to the cable boxes.  

That can't be done since your internet and tv connections must come from the gateway, not the ONT.  I may be missing something here in your wiring (i.e., whether it's exposed or behind the walls).   If the output side of the ONT (the one port that connects to the gateway) is exposed then why not simply move the gateway and dvr connected to it down there and use a shorter ethenet cable between the ONT out and the gateway?

I was thinking the same thing as @_xyzzy_   Move the gateway downstairs between the ont and the Ethernet connection to upstairs. Just be sure to keep the TVs on separate networks than your other devices. 

True I guess I will have to do.  I was just trying to keep everything neat and tidy.  Upstairs is my Rack with all my switches and network devices including NAT's and UTM/NExtGen firewalls.  Hence I wanted to have a centralized position, alas I guess I will try that. 

I assume you cannot pull another Ethernet cable from downstairs to upstairs? I don’t know a lot about networking. I’ve read of halving the cat5 to provide 2 connections. Might work for tv but if you have fiber speeds that my cause speed loss on the rest of your network. 

I was just trying to keep everything neat and tidy.

Another alternative could be pay the extra $10/month for a wireless receiver and stick it down stairs (assuming of course the wireless signal reaches).  That's pretty tidy albeit having to pay that extra $10/month!

He has a wireless stb downstairs now which loses connection. He’s trying to fix that problem.