Specs for Tablo Dual Lite Tablo DUAL LITE OTA DVR | Over The Air (OTA) DVR | Tablo
Ethernet 10/100
USB 2.0
Specs for Tablo Quad Tablo QUAD OTA DVR | Over The Air (OTA) DVR | Tablo
USB 2.0
Serial ATA II (3Gbps)
USB 2.0, Ethernet 100 and Serial ATA II are neither the latest nor anywhere near the fastest 
Yet, it’s likely unnecessary to ramp it up to achieve it’s needs.
I had the same problem plus a very low picture quality once connected. I use a firestick. Went into settings and eliminated 228mb in my cache all problems were resolved.
I also had the buffering problem but with the Tablo 4th generation and Fire Stick 4K. I didn’t see any buffering with just Fire Stick, but when the Tablo app on Fire Stick was chosen, Tablo would have frequent buffering issues. My Tablo is Ethernet connected to the router. The Fire Stick connected via WiFi 6 to my WiFi 6 router and despite the reported excellent WiFi speeds (I think 600 Mb/s), the Tablo kept buffering. In desperation, I bought an Ethernet adapter for the Fire Stick, Cable Matters Micro USB to Ethernet Adapter. Buffering problem solved. Note you have to change the Fire Stick settings to use Ethernet instead of WiFi. It will complain Alexa won’t be enabled on Ethernet, but I don’t use Alexa.
Several years ago I had the same issue. Not to harp on the network issue, but there are a few things you can try. If you have a smartphone do a speed test to see how good your speeds are. You also need to do a speed test on your streaming device, I believe you said it’s a Firestick. If your speeds are low, you may want to save funds for a mesh network. Don’t go with extenders, they will actually extend your network,but at lower speeds. Unfortunately, ISP’s typically use cheap equipment. We have fiber and the router they wanted us to use was garbage. I set up a mesh network and can sit in my backyard and get incredibly fast internet.