suspious similar SSID ( but Open)

So I was using my Android device, suddenly there was error in WiFi. It kept connecting and then disconnecting. Then at a point, it kept trying to connect but didn't. at this point i have had tried restarting router many a times

Out a sudden a similar SSID with Open connection starts to appear. I shut off and restarting the router also checked if the same was with another device. Now I use "forget" connection on my Android. and shut down the router. Funny thing open Network was still there. I connected and immediately within seconds disconnected. Then I think it was gone.Then turned on the router and relogin on network with the password and it is working fine till now.

I am freakin confused what happened here. anybody with help?