We provide some suggestions on what port numbers to use here:
For the Sonic Pad, it should be port 80 since it is Klipper based. Creality may not have the zeroconf discovery module enabled by default (meaning S3D cannot detect the IP address on it's own), but you can go into the network settings on the Sonic Pad to see the IP address and then enter that into Simplify3D manually. At that point it should be able to connect. If you're still having trouble, it might be good to make a dedicated thread on the troubleshooting subforum or email our team directly for help.