Network Manager does not connect to wifi on after restarting

Hi i'm currently using Debian 10, and my setup currently allows network manager to help connect to the wifi when the whole system boots up, but when network manager is rebooted, i lose connection and it won't connect again.

I'm currently using wpa_supplicant and network manager config, these are what's in the respective files

etc/wpa_supplicant/wpa_supplicant.conf

network={
ssid="xxxxxxx"
psk=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
}

/etc/network/interfaces

# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

auto wlp4s0
iface wlp4s0 inet dhcp
pre-up wpa_supplicant -B -i wlp4s0 -c /etc/wpa_supplicant/wpa_supplicant.conf
pre-down killall -q wpa_supplicant

i don't really know what pre-up is but it seems like it doesnt load if main system is already on... what else can i do?