There were Ctrl+E+C (comment) and Ctrl+E+U (uncomment) in older versions, or Ctrl+K+<
I went to menu: Tools → Options.
Environment → Keyboard.
Show command containing and searched: comment
I changed Edit.CommentSelection and assigned Ctrl+/ for commenting.
And I left Ctrl+K then U for the Edit.UncommentSelection.
These could be tweaked to the user's preference as to what key they would prefer for commenting/uncommenting.