Looks like the minimum speed requirement for streaming 4K video is 25 Mb/s. Just making sure - your DSL downlink speed is faster than that right?
If so, then it would be helpful to have your router model number as well as the DSL modem model.
I misread the original post -- now I see that you are connecting the streamer by WiFi.
Yes, as others have said, the modem needs to be in pass-through (modem only) mode. That means its WiFi will be off. I believe most Netgear stuff has a sticker on the bottom with its default IP address, user name, and password. You can contact the modem then from a Web browser on your network and check & change settings.
If you can run a cable from the streamer to the modem, why not run the cable from the streamer to the router instead? Most of them have 4-8 Ethernet ports in the back. (I just checked; yours has four.) If not enough ports, a $20 unmanaged switch will help.
Routers I’ve used consider wired and WiFi devices all to be on the same network by default. They draw IP addresses from a common pool. What I’m trying to say is, they can talk to one another.
(BTW, Category 8 cable is absolutely unnecessary at those speeds. Cat 5e is plenty, though there is nothing wrong with Cat 6 or Cat 7. My understanding is that Cat 8 is shielded and the shield grounding is said to reduce isolation between devices. Some very tweaky folks complain of higher noise floor, but I have no experience with that.)
6 Mb/s isn’t enough for 4K video (not even close). You’re able to watch video because it’s dropping down to a lower resolution stream. Check if you’re able to get Starlink satellite internet in your area: https://www.starlink.com/
@jgoldrick and @mike_in_nc If I do set the modem (Arris NVG443B - supplied by service provider) to passthrough will I still be able to connect my desktop and printer in the studio via ethernet to the modem (the router is in a different location in the house)? If so will they be behind a firewall? I think not. Could I add a second router for the studio? I have a lot of devices, though not many are hitting it at any one time (sleep mode).
@mike_in_nc No, NOT connecting the streamers by WiFi, only ethernet. The iPad that I use to control them connects by WiFi.
Cat 8 is infrastructure that I hope will be needed at some point. I wanted the shielding. I do not have a noise problem. I have replaced network switched power supplies with linear supplies, which does reduce noise though I can't say the difference is overwhelming. Ideally using fiber for the last segment would remove all noise, but neither of my streamers are able to accept fiber. Yes, there are ways around that... maybe someday, but bigger picture stuff first.
I am using an unswitched hub and I have indeed been into the modem and router settings.
I think I need to draw schematics of my current and preferred network. I know it is hard to get the picture from words alone. Later today or tomorrow.
Thanks to all.