MacBook Pro 15 (late 2011) keeps rebooting

See if you have a panic report (file's ending in .panic).  If you have more than 1, please post a couple as the differences can be very useful:

Look for the Kernel Panic reports at:

Finder -> Go -> Go to Folder -> /Library/Logs/DiagnosticReports 

<http://support.apple.com/en-us/HT200553>

The panic report should have ".panic" in the file name.

You can put the panic report in an "Additional Text" box when you Reply

If, AND ONLY IF, you have difficulty posting via "Additional Text"

then try posting to PasteBin.com, and give us a PasteBin URL link.

<http://pastebin.com/>

Try DriveDx, Disk Utility First Aid (examine the details for unfixed errors even if a green Ok), and try gfxCardStatus.

Also try creating a new user account, then reboot the computer and log directly into the new user account to see if you have the same issue. If a new user account works, then something is wrong inside your main user account.

Are you using Filevault?

Edit: link for creating a new user account:

https://support.apple.com/guide/mac-help/set-up-other-users-on-your-mac-mtusr001/mac

I don't see anything in the EtreCheck report, but I'm also not familiar with a couple of those apps such as the Palo Alto app and how they behave on macOS. Make sure the Palo Alto software and the Disk Drill & Virtual Box software are all up to date with the latest patches.

You may want to run DriveDx and post the report here using the "Additional Text" icon which looks like a piece of paper.

Try running Disk Utility First Aid on the drive. Make sure to examine the "details" to see if there were any unfixed errors even if Disk Utility gives a green check mark for successful completion.

There is also a chance you could be encountering a GPU issue which is common with the 15" & 17" models. You can try forcing the laptop to use the Intel GPU instead of the discrete GPU by using gfxCardStatus.

But post the etrecheck report, we might see something...

Pastebin is a good place to paste the whole report if you capture the URL while there…

https://pastebin.com/

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

Post the EtreCheck report here using the "Additional Text" icon which looks like a piece of paper.