The problem with 2009 model is the bluetooth and WiFi. There are upgrades available to fix that. Actually the WiFi module for an iMac will bring you up to snuff but you will need some antenna wire extensions.
You may be able to take the Bluetooth and Wifi modules out and replace them with USB versions. I have a couple of 2009s and one 1012 model but have not rushed into the upgrade as yet.
TheStickman have you upgraded the Bluetooth and WiFi on your 2009?
I’ve never had wifi on this Mac. Never needed it.