So I found a work around , well I read someone on reddit that managed to get it working! So you have to dowgrade to another version of the app. I went all the way back to app version Kasa Smart...

@Solla-topee Literally on the same boat as the initial poster. Purchased a new modem, was eligible to receive the KL430. And just doesn't connect during the pairing process.... ( That's literally all...