Internet connectivity is an obvious candidate for this. Could not connect to server? Check if WiFi is on. Check if Dns is working. Check if ping to router is w

Internet connectivity is an obvious candidate for this. Could not connect to server? Check if WiFi is on. Check if Dns is working. Check if ping to router is working. Check if ping to google is working. Link to wifi settings. Whatever you do. Just don’t do this the reverse way, like my smart ass Samsung tv does! It determines if internet is working by pinging a Samsung server, before it even allows other apps to use their internet. You can probably figure out what will happen when Samsung servers are down.