The Amazon firetv micro USB to ethernet port + micro USB female port, does not work
https://www.amazon.com/dp/B074TC662N/ref=cm_sw_r_other_apa_i_YsUXEbTTZ959Y
There is definitely a fire TV ethernet adapter.
A Pi will almost certainly result in a better end product, however it may take more work on the user's part to get there. Nothing crazy, but he or she may need to set aside an afternoon to follow a guide.
On the FireTV he or she will have to sideload and are locked to Amazon's OS/drivers, but it's easy peasy.
Definitely a matter of preference.
IT Guy here. You have a wifi problem. I have a very nice WiFi router myself... Asus RT-AX86U and even it will make stupid channel choices if left in auto mode. If I force the 2.4GHz and 5Ghz radios onto the right channels, it has amazing range and speed.
You probably need a better and well configured Wifi router. You also need to do some speed tests throughout the day/week to ensure that your internet provider is actually serving you the 500 mbps that they are charging you for. For people that don't like to fiddle with routers, I usually recommend replacing the whole system with a two or three node mesh network. TP-Link makes a pretty decent one that won't break the bank.
If you just want to solve this FireStick/YTTV buffering problem then the cheapest thing to do is run an ethernet cable to your firestick. Honestly, spending a little money to have your expensive internet connection cover your entire house properly is worth the time and effort but I understand most people don't get as focused and picky about that as I do.
These did not work:
Generic USB-C Hub Sold under different names.
The USB-C ones work with the Chromecast with Google TV, Raspberry Pi and various Macbooks & PC's.
I have the ChromeCast Ultra adapter but have not tried it yet with the Stream 4K. I only have the Ultra because it was free giveaway by Google.
Yes, they offer an Ethernet adapter for fire sticks, though I am not a huge fan of dangling a bunch of stuff off an HDMI port (seems like a lot of mechanical points of failure).
https://www.amazon.com/Amazon-Ethernet-Adapter-Fire-Devices/dp/B074TC662N/
I second the "use Ethernet" recommendation.
Edit: Also, locals are typically 720p for ABC/FOX and 1080i for NBC/CBS, because that is what the corporate networks produce. My PBS is 1080i and my CW is 720p, but I don't know how standardized those are.
what speed do you have (down speed not up) ? Is your stick connected wirelessly or via a network cable (RJ45)? If wireless how far away from your router is your stick? how many other devices use the wifi in your house? What wireless connections does your wireless router support ( A/B/N etc etc)? What is between your router and stick (Brick wall/s drywall)? Have you checked the wifi signal strength by your stick?
https://www.amazon.com/WiFi-6-Router-Gigabit-Wireless-dp-B08H8ZLKKK/dp/B08H8ZLKKK/ref=dp_ob_title_ce
Have you actually ran a speed test on your network?
also instructions for running a speed test on your stick:
https://www.firesticktricks.com/test-internet-speed-on-firestick.html
I know it's a lot of questions but all these things impact your connection. I hope this helps you and others as well.