I would start with making sure that all the drivers and firmware are up to date. For the firmware, you can use the LifeCycle controller (LC) to perform the updates. This video will show you how to do the firmware update, but its missing the part where you choose which network connection to use. If you havnt used the LC for firmware update before, it will ask you to configure a network port that will allow connection to the ftp site.
if you try to connect to the ftp site and you get a DNS error, try using the ip address for the ftp site: 188.8.131.52
if the system isnt in use, you could try powering on the system and let it sit at the bios boot menu for a few days. if it doesnt reboot, I would look at an OS issue or an environmental/power issue.
Hi DELL-Rey G,
thank you for reply. I will try updating from FTP in next days, as server is in production now and I must find a time window with low load. In attached screenshot, as you can see, almost all FW versions are up to date.