Using the WD Wireless Pro as a Plex Server (using built-in Plex functionality in WD). I have an iPhone and an iPad Pro (2018 12.9"). My iPhone and latest Infuse and Plex apps works fine. My iPad works fine with Plex app. But with Infuse on my iPad, it only works when the WD is connected to the internet (so that the iPad has internet). I have specifically turned off the WD "Connect to Internet" function as many places we want to use this (while traveling on a plane or in a hotel room, etc.) will not have internet.
With my iPad connected to the WD WIFI (5Ghz band, no internet), I launch Infuse and can choose from My WD Passport or OURPLEX (our Plex server at home). I choose My WD Passport and I immediately get "An error occurred. Sorry, Infuse encountered an error while trying to connect." Plex app works fine. Reconfigure the WD to connect to internet, and turn off and back on iPad WIFI (5Ghz WD Wifi) so the iPad has an internet connection (through the WD) and launch Infuse. Works fine.
So, on my iPad, connected to the WD WIFI and no internet, Infuse gives an error and cannot connect. With internet on the iPad and connected to WD WIFI, it works fine.
On my iPhone, Infuse works fine with or without internet.