pcManFM (the file manager in desktop version of Raspbian) suffers from a digital form of "demetia", and no fix in sight. no use demanding for that functionality, its a free app anyway.
some have changed to Thunar which I have tested on another OS on another SBC.
Thunar always connects to the network drives upon reboots (if you set it to remember passwords forever)
I, on the other hand, for network drives that I need to connect to every time my RPi boots, mount those network drives via /etc/fstab.
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"
Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"