Since you have a SA Doser and plan to have the P4 control it, you first needed to set it to slave mode otherwise the P4 cannot control the doser. A master device cannot control another master device. Go back to your PAB page in the P4 settings and press SYSTEM reset to remove this doser from your PAB device list, then disconnect the PAB cable from the SA Doser. Afterwards, connect to your SA Doser via USB or hotspot and set it to slave mode. It would also be good to update all your native SA Doser and P4. Outdated FW will not work with the IOND.

https://www.aquariumcomputer.com/kno...to-slave-mode/
https://www.aquariumcomputer.com/kno...oser-firmware/
https://www.aquariumcomputer.com/kno...ux-4-firmware/

Once your devices are updated, you can procced with following the IOND setup steps:
https://www.aquariumcomputer.com/kno...-setup-part-1/

If you continue to have trouble with this, please open a support ticket for 1-on-1 assistance.