Not sure about the issues with your laptop and printer.
I do know that IOS 12 added 'private address' as the default for iPhones. To reduce this privacy risk, iOS 14, iPadOS 14, and watchOS 7 use a different MAC address for each Wi-Fi network. If you don't like this you can disable it.
After updating to IOS 12 my phone showed up on my Wi-Fi as an Unknown device (previously appeared as APPLE) with a new MAC address.