Pulse P300 not visible in app/ weakly blue blink

I have a couple og pulse 300..10 years old. I have had Them wireless connected but suddenly one has disappeared from the app. Tried reconnecting, poweroff several times... It blinks weekly blue...and at the same time the light in the ethernet port is blinking. Exact same Thing happens if I connected with ethernet. What can I do to get the speaker on Line and playing again? Thank you very much,