My all wifi switches went offline after router factory reset. I make a settings backup befor factory reset and restored router settings with previous SSID and password.
Please help me. How can i back all switches online again with out re-flash.
The first thing to find out is if the wifi devices are actually connecting to your wifi. You can probably tell from your router by checking to see what devices are connected.
It may be that they all have different IP addresses. Did you have the IP addresses defined in the router, or are they statically defined in each node?
How can tell from router by checking to see what devices are connected. I have
router ASUS RT-AC66U. All other devices those are connected I can see there.
I don’t know your router, but somewhere it will have a list of connected devices, possibly under a DHCP title, listing the dhcp leases it has handed out.
Thanks for your answer 
all devices came back automatically after 2 days.