OpenHab stopped working on wifi

Installed on Rpi3, it was installed and had some things setup and running too fine till yesterday. But from today I am not able to connect to Wifi. I tried using three different wifi connections. I tried a fresh install on a new Rpi3, same problem. Just wont connect to Wifi. Any solution?

Did you use rasp-config to set the country location and other configs prior to continuing any OH configs?

Maybe a stupid question, but did you check your WiFi router/AP?

Yes I did check wifi router. I have 2 installations. One is working and another is not. both connected to same wifi router

No I did not use rasp config. I had installed in another Rp1 the same way 3 days back and it was working in wifi. This new installation is not working. So didnt try doing anything different than what i did last time.

Is that necessary and how do I do it?

You do not need raspi-config to configure your WiFi, there are more ways and as your wifi previously worked then your method is good as well.

Ofcourse you CAN use Raspi-config to configure it and you do that by tuping:
sudo raspi-config in the cmd line, but as you have openhab, you may need to do :
sudo openhabian-config

I must admit though that when I used raspi-config to change my credentials, it still didnt work. Inspection of my wpa-supplicant.conf file showed it had kept both credentials (old one and new one). I had to remove one to be able to connect to my new credentials

It didn’t work previously. My first installation on a different RPi3 worked in Wifi. I repeated the same installation on a second new RPi3 and new SD card is not connecting to Wifi, but is working on LAN wired. SO was wondering what could go wrong when both the installation was done exactly the same way.

what does your /etc/network/interfaces file say?