It doesn't work with fstab on Solus, idk why. But you have to work around it with systemd automount. I wrote messy script that handles everything, but there are guides on the internet, e.g. this
They tend to differ in the mount options used.
My script:
#!/usr/bin/env bash
#automount nas
echo "------------------------------------"
read -e -p "smb share name (used for mountpoint, no dashes):" SHARE
echo "------------------------------------"
echo "------------------------------------"
echo "making .cred file for smb share '$SHARE' ..."
echo "NOTE: Credentials are stored in plain text but with root only reading permission"
read -e -p "smb share username:" USR
read -e -p "smb share password:" PW
read -e -p "path to cred file:" -i "/etc/samba/.cred$SHARE" CRED
read -e -p "SMB Path (//IP/path):" -i "//192.168.100." SMBPATH
echo "------------------------------------"
echo "------------------------------------"
echo "storing cred file in $CRED ..."
printf "username=$USR\npassword=$PW\n" > cred$SHARE
#overwriting credential variables
USR="lol"
PW="lol"
sudo mv -v -i cred$SHARE $CRED
echo "------------------------------------"
echo "------------------------------------"
echo "making .cred only readable by root ..."
sudo chown root:root $CRED
sudo chmod 700 $CRED
echo "------------------------------------"
echo "------------------------------------"
echo "sudo mkdir /mnt/$SHARE ..."
sudo mkdir /mnt/$SHARE
echo "------------------------------------"
echo "------------------------------------"
echo "generating systemd .mount and .automount files ..."
touch mnt-$SHARE.mount
printf "[Unit]\nDescription=$SHARE SMB Mount\n\n" >> mnt-$SHARE.mount
printf "[Mount]\nWhat=$SMBPATH\nWhere=/mnt/$SHARE\nType=cifs\n" >> mnt-$SHARE.mount
#mount options:
printf "Options=credentials=$CRED,user,uid=1000\n\n" >> mnt-$SHARE.mount
printf "[Install]\nWantedBy=multi-user.target\n" >> mnt-$SHARE.mount
touch mnt-$SHARE.automount
printf "[Unit]\nDescription=Automount unit for $SHARE SMB Share\n\n" >> mnt-$SHARE.automount
printf "[Automount]\nWhere=/mnt/$SHARE\n\n" >> mnt-$SHARE.automount
printf "[Install]\nWantedBy=multi-user.target\n\n" >> mnt-$SHARE.automount
echo "------------------------------------"
echo "------------------------------------"
echo "moving previously generated systemd .mount and .automount files ..."
sudo mv -v -i mnt-$SHARE.automount /etc/systemd/system/mnt-$SHARE.automount
sudo mv -v -i mnt-$SHARE.mount /etc/systemd/system/mnt-$SHARE.mount
echo "------------------------------------"
echo "------------------------------------"
echo "starting systemd service ..."
sudo systemctl daemon-reload
sudo systemctl enable --now mnt-$SHARE.automount
echo "------------------------------------"