CCR1009-8G-1S-1S+ Reboot Kernel Failure

I have several of this router acting as PPPoE servers.
When I upgraded them from v6 to v7, som e of them crashed, and I had to use Netinstall to wake them up.

They have been working fine for several months now, but now the ones that had a problem when upgrading are starting to reboot, and log ar saying probably kerner failure.

Anybode else had the same problem, or any advice on how to fix it?

Do they have the latest version 7.3.1 ?

Yes. They do now.
First they where running stable with 7.1.3 but after they startet crashing I upgraded them, but they are still crashing randomly. Sometimes several times with minutes aparts, and sometimes they can run for 1-2 days.
The stranges thing is that they seem to be chrashing at the same time (not exactly, but within 20 minutes)

This is causing a lot of problems and complaints, so I have to try and replace them if MikroTik doesnt come up with an answer soon. (I have contacted support, but no reply yet)

same issues on 1036 with 7.2.1 and 7.4