10 minutes, I’d agree, is ridiculous. Mine takes less than a second, certainly, so my guess is there is something wrong in your network or setup.
But your speed to the internet (that 450 Mbps you’re talking about) has little to do with the Sonos connecting to your router, it is only an indication of the speed of data from the outside world being handed to your router.
The first thing I would do is a simple refresh of your system. First, check for any updates from Sonos. After that, unplug all your Sonos devices from power, and then reboot your router. Wait two minutes, then plug back in your Sonos devices. Wait another two minutes for them to boot up and reconnect, and test. If you’re still experiencing that 10 minute start up delay, I would recommend that you submit a system diagnostic, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, they get sensitive about GDPR.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.