Hi,
In theory, BeoPort won't work with a BeoSystem 2500.
In practice, it can work, but with limitations.
You need a BeoLink converter box type 1611 to connect both units, the BS2500 via Datalink, and the BeoPort box via Masterlink.
You'll have to setup the audio system to option 0, and the BeoPort box to option 2 , and connect your Beolabs + infrared sensor to the BeoPort box (that will become your main audio system). If you have a video system, it won't work (sorry!).
BeoSound 1 being a non-BeoLink system, you can only send the audio from BeoPort to the AUX input at the back but without any control on BS1.
Reunion Island is greeting you!