I assume you get this message when you try and load the app on a smart phone? If so it sounds like the smart phone you are using is quite old and is running an old version of Android; It needss to be version 5 or higher. If the phone is newish then the message is odd and I'm at a loss how to sort that. You could load the app on a tablet, android or apple, either should work just as well.
Do you have a particularly pressing need to change the password?
My Samsung Tablet (TM-800: Galaxy Tab S) is 6 years old but it's running Android 6.0.1. Have you tried to update the tablet operating system? If not, a quick Google should tell you how to do it.
But then maybe just changing the passwords on all your devices may save you time but I understand why you currently dont want to 🙂
@Pedigree500 I am connecting via the ethernet cable
@BAFlyerI will change all the passwords at a convenient time. I have tried updating the Tablet and it won't. It's running Android 4.
@licquorice I've got a load of devices that I need to give service quickly. If I can just change the WiFi Password I can get them all working now and change them at a convenient time later.
Wif you are connected to hub using Ethernet then you should be able to change password without a problem unless there is something in your password which is not acceptable to the hub. Unfortunately I don't think if gives a clue to the problem just won't update