My device was always offline but others were active I tried many time add and remove but nothing was working out.
K here is the trick, other device that were active they were running through LAN network whereas the offline one was working under WiFi signal. What does this mean to me. LAN network works though data on the WiFi is finished and meaning that u wouldn't realise that data is finished because other devices are working. Until l load up data on the WiFi I've managed to remove offline device and add it again after that I switch it off and on again it went LAN network.
LAN network you can operate your device anywhere. That's my story