Android connection issues?

I am unable to connect to MyCloud from any of my 4 Android devices, receive an "Invalid request (404) message. This is a fairly recent situation, days, possibly a week or so, no more than a month. No problem with any of 4 Win10 laptops. I have uninstalled and reinstalled the app on one device; they see the device is listed, but cannot connect. Suggestions?

@jwb Have you already gone to the Dashboard under Cloud Access to see if they show as connected? See image below. At top is my cell phone and bottom is my tablet.

If they are then I would reboot my My Cloud device and then reboot my router to see what happens.