Two suggestions. First, make sure your new router is using the protocols as delineated in the Sonos Network Requirements FAQ. Second, follow the suggestions in the new router - installation instructions FAQ. The thing I’ve found most useful is to wire one of my Sonos units temporarily to the router with an Ethernet cable, which gives me access to most of my speakers, so I can change my network data. For my Roam, I just follow the instructions. I suppose you might go the easy route, and just set up the new router with the same SSID and password. Assuming it’s broadcasting the same protocols, your Sonos would just connect. 

If you're having trouble connecting your Sonos Play 3 and Play 5 speakers to your Box Broadband, start by ensuring that both speakers and your Box Broadband are on the same Wi-Fi network and that your Sonos app and speaker firmware are up to date. Try restarting your Box Broadband router and the speakers, and within the Sonos app, check network settings and ensure the speakers are on the same frequency. If your Box Broadband has both 2.4GHz and 5GHz networks, make sure all devices are connected to the same frequency. Consider adding a Sonos Boost to your setup for a dedicated Sonos network. 

Moved Play 5 to a new home and it won’t connect to new WiFi network.  Getting confusing message router technology that I don’t understand.  Should I just unplug and replug the router first?

Are there any other SONOS units on the network?

I’d at least temporarily wire the PLAY:5 to your new router. Once it is working, you could remove the wire.