Once you have installed panel and in case the server does not boots properly on reboot then one of the possible reasons must be LVM issues.
XenServer might fail to activate virtmedia LV created by Virtualizor to store OS templates.
When you give a repo size while installing panel, virtmedia LV is created of that size.
An entry is also made in /etc/fstab file.
If the server is failing to boot and you see login for maintenance mode in your server’s console then you can login there and comment virtmedia LV’s entry in /etc/fstab file with a # at the start of the (sample) following line :
#/dev/VG_XenStorage-ae846e0d-ab65-7b31-d206-e4d63deaeab4/virtmedia /var/virtualizor ext4 defaults 0 0
You can then boot to normal mode .
Once its booted to normal mode successfully, it is confirmed that the issue was due to virtmedia LV.
So to keep the LV mounted, you can add an entry in /etc/rc.d/rc.local file assuming its permissions are already set to execute.
Taking the above LV as an example, you can use following line :
mount /dev/VG_XenStorage-ae846e0d-ab65-7b31-d206-e4d63deaeab4/virtmedia /var/virtualizor
chmod +x /etc/rc.d/rc.local
You can reboot the server to confirm if everything is working fine.