new to smart home

i have Aqara E1 hub (free gift from A100 lock)

now my house got

1. E1 hub
2. A100 lock (bind to E1)
3. 1 gang D1 (bind to E1)
4. 2 gang D1 (bind to E1)

in Aqara app i can control on/off and see the status of devices (at home connected wifi or outside with cellular)

in homekit app can see as well, when i at home connected to wifi, no issue, but when i am away from my house using cellular, it show accessories offline in homekit app (aqara app no problem)
in fact, i use the iOS homekey to unlock A100 no problem

noob question here, is it i have to get homekit hub? so that my homekit app only can see accessories online

okay, thanks for the info, will wait for the new Apple TV to reach Malaysia