Additionally, if the wifi you are using is 5Ghz and the Roku in question is farther away or has more obstacles between itself and the router, you can try switching to your 2.4Ghz wifi. I common misconception is that the higher the frequency the better the wifi. This is not true in all situations. Lower frequency wifi has longer range than higher. If neither of these works well, you might consider an extender but that can cause undesirable latencies.
On a side note I only just realized that Ethernet isn't even an included option in the latest Rokus other than the Utra, which is probably why I bought the Ultra for my first two. Wifi can be very finicky so I always look for devices with Ethernet options just in case.
onn Roku 43" TV model 100012584 running version 12.0.0
Twenty plus years of online experience as a web developer, general user and consumer. Recording engineer. Sixty plus years of troubleshooting and problem solving in several fields. Here to help and get help when I have issues with Roku. Nothing more. Not here to socialize. That's what real life is for. 😉