I think there’s some confusion here. What is a Sonos 1 and Sonos 2? Are these speakers?
There’s a great article around here written by one of the members on how to reduce wifi interference and connection issues.
The speed of your internet is only tangentially important, what is more important is the ability for your Sonos device to be able to reliably and constantly be connected to your router.
The controller on your i7 is only a remote control that talks to the real application which runs on your speakers, and tells them where to reach out to get the music stream. If the speakers are disconnecting from your router for any reason, then they could lose either the instructions you’re giving them from the i7 or losing the stream they’re told to reach out and get on the internet outside your home.