Airdroid Web Connection problem with Samsung S6

Hi All, on my Airdroid account I have configured 3 phones: 1 ASUS that works perfectly and 2 Samsung S6 which are experiencing this issue.
For sure I am able to connect on the 2 Samsung S6s only when I have just booted them. Then, after a while (a random time period), they become unreachable from Airdroid.
Both S6s are configured in the same way and the 3 phones share the same kind of Airdroid 3 configuration.
Nothing changes if the network is WIFI or 4G.
Can someone help me?
Thanks!!

Hi All, on my Airdroid account I have configured 3 phones: 1 ASUS that works perfectly and 2 Samsung S6 which are experiencing this issue.
For sure I am able to connect on the 2 Samsung S6s only when I have just booted them. Then, after a while (a random time period), they become unreachable from Airdroid.
Both S6s are configured in the same way and the 3 phones share the same kind of Airdroid 3 configuration.
Nothing changes if the network is WIFI or 4G.
Can someone help me?
Thanks!!

Any error messages? Try if this guide helps: [Help & FAQ] Failed to Connect to Device?