When you are attempting to connect, can you ping the printer? If connecting from an iPad you will need an app store utility to ping.
There are a bunch of free ones, I've used "Network Analyzer Master Lite", it does not actually ping, instead it has a "network scan" that works pretty well.
For example, "bfd.lan" is a Duet WiFi running reprap 3, "jubilee.lan" is a Duet3+Pi
LanScan.PNG