@Peter-Mason I have a similar situation at home. Network Printers, NAS, security cameras and IoT devices that all get Static IP's. Be warned there is a web UI but you cannot configure the router from it. You have to use the mobile app.

The Amplifi HD has a 4 port switch built in so you can wire your Synology NAS to it.

You can set your DHCP range. The router defaults to 192.168.156.0, but it is easily editable. You however cannot set the Router IP. It will default to ..*.1 for whatever subnet you choose.

You can configure the same SSID and Password. Most devices won't care, but some may need to be setup again if they see it as a new network. If you setup an additional SSID the router will add a suffix (-2g or -5g) to the name.

Reserving Static IP's can be done, but it has to be done through the smart phone app and you will have to type the Name, IP, and MAC Address using your small smart phone keyboard. There is however a Family section in the app. It allows you to group devices so you could pause Internet for a group. That section of the app lists all connected devices and if you select one you get a Static IP reservation option. If you go that route you might not need to type the MAC Address.

I have a list of issues posted here: https://community.amplifi.com/topic/1238/new-amplifi-hd-issues. I'm going to be returning mine for a refund. I would suggest you keep looking.

Good Luck!

Considering Amplifi but have some questions....