Can you check whether you have latest BIOS and iDRAC FW installed on the server? You can also check System Event Log, Lifecycle Log and POST code in iDRAC to see whether it have any useful information. 

Hi, thanks for choosing Dell. I'd recommend to contact the phone support if you're system in in warranty for LC log checking but in the meantime please run this.
https://dell.to/2VuP6IS
Your system(or OS) is not working, so watch dog time out had to be turned on for recovery.

They are definitely outdated, but I'm nervous, what if the watchdog timer decides to reset the system during the actual update process? The logs simply say the watchdoing timer triggered, but it gives no further insight. The server is now up and running and so far no reset has occurred. It seems to happen only during the bootup process (and always at the same point in this process).

Hello mauricev,

You mention it occurs every so often. Is that weeks, days…? If you are up and running you will likely be able to update the firmware no problem. Focus first on the BIOS and iDRAC firmware. If you are very far behind you should step up firmware instead of jumping to most current.

See if this applies to what you are seeing and be sure to update OMSA to latest supported version.

https://dell.to/3fy1hff

Optionally disable watchdog in the system BIOS and see if it gives you different behavior like it may hang or reboot in a different spot or log additional information in the system logs.

   You can disable watchdog in the BIOS > integrated devices > OS watchdog timer  near bottom