scanner failing to open

The MFC-J6545DW supports Airprint (built-in driver in macOS) and the Brother support website says that if that does not work you should install the Brother iPrint & Scan application, which is available in the Mac App Store. (There is also a Firmware update dated 6/2/22 for the MFC-J6545DW that you should probably also install. See https://support.brother.com/g/b/downloadlist.aspx?c=us&lang=en&prod=mfcj6545dw_us&os=10072 for the Brother/Monterey downloads)

The MFC-J497DW has similar directions on the Brother Support website. In the case of the MFC-J497DW there is also a firmware update, dated 6/16/22 at https://support.brother.com/g/b/downloadlist.aspx?c=us&lang=en&prod=mfcj497dw_us_eu&os=10072 for Brother/Monterey downloads.

This information is all on the Brother support website.

I don't understand your comments about HP, Epson & Canon ... are you saying you also have HP, Epson & Canon devices and they also do not connect? How are you trying to connect them?

I strongly suggest using a direct USB connection (no hub) until you have succeeded in getting each device working. After that you can try LAN or Wireless or NFC.

No way to help unless you identify the exact make & model scanner, how it is connected to your Mac and whether or not you installed the drivers.

The -21345 error code suggests missing drivers or a bad connection.

Look in About This Mac > System Report > USB to see if your Mac "sees" the scanner. (That assumes, of course, that your scanner is connected via USB and that it is turned on.)