You posted in the wrong thread 
The Samsung Connect is different from the V3.
You may want to try connecting by Ethernet and see if you can change it once they are connected. I do remember seeing a similar post recently: https://community.smartthings.com/t/samsung-connect-home-smartthings-wifi-0-47-10-all-zigbee-devices-went-offline/265212/10
Alas there was no resolution in that post.
try connecting by ethernet and see if that helps you get them back online.
Contact ST support if you are still unable to connect them.