@LLW7
This is a known issue with cable ISP like Xfinity/Comcast, Cox, and AT&T and their router firmware.
You will need to verify that the "Wireless Mode" under your 2.4ghz settings are set to b/g/n.
Try logging into your router or using the Xfi mobile app and "Edit" the 2.4 ghz band. https://www.xfinity.com/support/articles/change-wifi-mode-admin-tool-xfinity-xfi
Restart both the Router and your Roku devices after making the above changes.
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Some users may need to contact the ISP in order to make these changes as new updates to the routers have been made disabling the ability for users to make these changes themselves.
If you need more help post back with both the Roku model numbers (Settings/System/About) and the router model number.
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