Ubuntu: Mount Windows-Share on startup

Install cifs-utils

sudo apt update
sudo apt install cifs-utils

Create directory to use as mount point for the Windows share

sudo mkdir /mnt/winshare

Mount Windows share manually using terminal

sudo mount -t cifs //servername/share /mnt/winshare -o username=shareuser,vers=3.0

If supported use Version 3.0. Otherwise use a supported version (For example: vers=2.0)

Mount Windows share on startup using /etc/fstab

Create file with credentials

sudo nano /etc/cifs-cred

username=shareuser
password=password

Set correct permissions so that no unauthorized user can read the file

sudo chown root /etc/cifs-cred
sudo chmod 400 /etc/cifs-cred

Add record to /etc/fstab by using nano

sudo nano /etc/fstab

//servername/share /mnt/winshare     cifs     credentials=/etc/cifs-cred,file_mode=0777,dir_mode=0777,vers=3.0     0    0

Test it

sudo mount /mnt/winshare

How to unmount

sudo umount /mnt/winshare

Now reboot and check if share gets mounted automatically