@marcilovieira23
As a general rule, your Roku devices are designed to be placed on differerent networks and internet providers without needing to reset or factory resetting the Roku device. You should be able to just connect it to your new internet and be good to go. This is what makes taking the Roku device (and its remote) convenient for traveling.
With the above being said, there are a few issues with some ISP (internet service providers) and Roku devices. With AT&T, if you have a 2.4ghz-only Roku device, you will likely want your router configured so that its 2.4ghz Wireless Mode is set to b/g/n. With the 5ghz band, some AT&T routers are using DFS channels (52-140). Roku devices cannot see or use DFS channels currently, so you will want to make sure that you have at least one (1) 5ghz band/radio broadcasting a non-DFS channel (channels 36-48, or 149-161).
Also, make sure you have a working physical Roku remote as you will be switching networks. Otherwise, you will need to have to rename your new AT&T network to the same SSID (network name and password) as your previous Comcast network in order for your Roku devices to connect.
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You can point the AT&T installer to the above info if you need to and they should be able to verify and set everything up.
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Feel free to add to this post if you encounter any issues after your new network/internet is installed. Make sure to include any Roku model numbers from Settings/System/About and your new router model number so info can be more narrowly tailored to any issues you might encounter. Hopefully all will go smooth for you.
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