In relation to the many, many posts I have read re the very same issue of the Roku losing internet connection while stating that the speed is not sufficient, having to reboot the unit and your router every time you want to watch Roku.
When this happened to me, I'd go into my Router's GUI and notice that the Roku had been placed in my DOS attack Black List, rendering it useless as my Router recognized it as attacking my network! The Roku sends/receives a great amount of data and the more you watch the more it sends/receives. My Router sees waaaaaaay too many packets being sent/received which is just normal for the Roku, but my Router doesn't know this. Hence, it is placed in the Black List when it's lost connection. Perhaps your Router security is too high or too strict. Do you all notice that this happens more on the device you use more than the other Rokus in your home? Have a look at your Security settings in your Routers!
That's a good observation. I'm not certain how many users have routers that offer than level of security. I know my CenturyLink DSL modem has nothing that severe, but then I've also never had the network connectivity issues that others have reported.
And in case anyone is wondering: DoS is short for Denial of Service. That's when bad/stupid/annoying people attack a web service with a barrage of packet hits that overwhelm the service and basically shut it down for genuine users.
Could also be your Roku device's normal pinging of your router to ensure a connection is available. Some routers can be configured to ignore such pings. Others don't like repeated pings (especially if you have high security settings) If you can't find a suitable setting in your Security settings to address issue to allow stable network connection, or is not available, you can just disable these pings at the Roku device.
To access Platform Menu... Home5x,FF,Pause,Rew,Pause,FF.... Wireless Screen...Network,,,Disable Pings
Keeping pings Enabled will have Roku automatically checking for connection (communicating with router), so disabling may mean having to manually connect to network more after a dropped connection. But if automatic pinging is causing disconnecting, or your router is perceiving a threat, well...
I happened again yesterday, of course, as I knew it would. OP, here, and I went immediately to my router's GUI to verify that the Roku landed in my Dos attack black list as usual - it did. I then reviewed some data via the GUI to find that all my other devices are showing packets received in the few hundred thousand range - 217.234k, for example. The Roku, however, showed 2.5 MILLION packets received so no wonder my router thinks I'm under attack, and maybe I am??? I don't know. I can stream other apps such as Tubi, Pluto, Peacock, etc all day every day with no issue. However, each time I stream YouTube for about a few hours, I'll lose connection due to the scenario described. I saw a post by another forum member who essentially described the same issue, but said poster loses connection ONLY while streaming the Roku channel. Very strange.