R6700AX issues with Roku's

I had an older Netgear router in an out building that ran 5 tv's either with roku's or via smart tv's. I replaced the older router with a neatgear R6700AX router and it triples my speeds which was nice however the roku's struggle..... either get standard definition quality or its says not connected to the internet. The main TV in there is a smart TV, and it works as it should. So I replaced a few of the rokus thinking maybe they were outdated or worn out but the new ones are just the same. I'm assuming it must be a streaming limit or something? but the older outdated router could run them all plus other stuff out here...... so I'm confused by that.

I have another AX6700AX in a barn where I have a golf simulator...... and I put a few tv;s out there..... same thing..... roku's, if they'll even connect can only produce grainy feed with buffering...... all while getting over 600 mbps. The simulator never has an issue?

I am obviously not very tech savvy but I feel like these newer routers should easily be able to push all of these roku's and that maybe the routers are simply set up incorrectly for what I want them to do. or maybe it's a compatibility issue with rokus..... but the older router never had an issue..... and my modem/router combo in my house runs a bunch of them without issue..... so I assume compatibility isn't an issue.

Any help would be greatly appreciated