Air carrier Captain reported the DG cargo was improperly placed for air transport. Ramp personnel secured the DG cargo and the flight departed.

Narrative

Dangerous Goods (DG) ISSUEWe had diverted to ZZZ due to weather in ZZZ1 (from ZZZ2). Upon landing the company was working on plan C or D for our freight bound for ZZZ1 and us and the freight bound for ZZZ3 while trying not to get us to time out. ZZZ1 freight was removed and they discovered we had mixed DG. They pulled the DG for ZZZ3 and put it in a can; loaded it; and the FO went to inspect. He came back up and told me they had loose boxes. I went to see and found multiple boxes containing DRY ICE just stacked loosely on netting and not even straight nor secure. I told the crew they needed secure it and had limited time before we timed out physically from the long night thus far. They secured it and we departed. FO told me the Ramp / DG Agent said they told him they 'hadn't done this in a while'. Neither of us knew what he was referring to but my guess is the regular DG person had already left for the night / day as this was pushing past XA:00 am and the sun was coming up.I'm sure the ramp felt the pressure from Dispatch/ recovery / everyone....But it was a simple; 'nope; secure it'.Suggestions: Taking our time and double checking each other. Not sure if he was the only DG agent left but enough of them have been around long enough to know loose boxes in the Accessible Dangerous Goods Unit Load Device (ADG ULD) isn't ok.We were all tired and a good portion were wet. Thunderstorms were passing through the area with heavy rain bands hitting the ramp/airport.The ZZZ Ramp personnel did a fantastic job of juggling 3 planes when they didn't expect the extra one much less the extra fright.