Airdrop not working; Bluetooth connected. Did all other troubleshooting too I am trying to send some docs to my MacBook through Airdrop. Problem being, I have tried almost all suggested troubleshooting, tried restarting systems, took care if the devices were having DND mode on, or were on Sleep, the Bluetooth is also shown connected. But still the Airdrop of either of the devices is not showing the other device available in their respective Airdrop section. 
This has happened quite a lot of times with me, since past many months. 4/5 month wrt delay in connectivity.
Please suggest why it could be happening and what can be done to let Airdrop work fast.
Handoff and Airdrop would possible not works in anytime in my experience when on iOS 12, it works better when comes to iOS 13 but could still fails.

And this morning I found a why while my MacBook and iPhone could find each other but my iPad, reason is the IP address of iPad is 192.168.8.xxx while MacBook and iPhone are within 192.168.9.xxx.