hello i have a problem that wirless signal dissapear and no internet when iphone is locked buy when i unlock it the internet comes back
how can i fix that
any help ?

1) This is unrelated to MikroTik, or RouterOS.

2) It's common for smartphones to go into power saving when you lock them / put them into standby mode with the power button.
Same for Galaxy S8, use power button to put it into standby, WiFi gets turned off.

These are normal power-savings features.

On some Androids you can adjust this, on others you can't (depends on how the manufacturer configures the OS on the phone).
I do not know if this is something that can be configured on iOS.

Thomas is right. All phones will do this. If your phone will need to download something, it will turn on the WiFi automatically.

Extend wireless security profile / group key update to 1h and DHCP server / lease time to 2h and your iPhone will be connected to wifi between screen wake and unlock.

Thomas is right. All phones will do this. If your phone will need to download something, it will turn on the WIFI automatically.

nescafe2002 is right! When the IP leasing is expired, which the default is 10 minutes, clients can't receive packets! Increasing expiry time at the DHCP server resolves this problem!