MX100 stucks on version 13.36, will crash all credit card machines if apply newer firmware

[TTS]

Hi everyone -

I have been having this ongoing issue for year. If I apply new firmware (stable or beta), all my credit card machines and postage machine will be crashed and not responding. The logs on Meraki does not really tell me anything.  Usually, I have to rollback the firmware and cycle the power on machines. It happens randomly and I can't wait to call support and troubleshoot on the issue since we need to take a payment. 

Anything from my end that I can do to troubleshoot when it happens? 

[PhilipDAth]

You need to get a test MX and a test credit card machine and setup a test network.

Do the upgrade.  Then when it breaks open a support case or start analyzing it further.

[TTS]

I have another MX unit that will be used for HA (no license). If I use that unit for testing, can Meraki support check on the unit?

[PhilipDAth]

I would check the security centre in case IPS has blocked something (like an insecure protocol or an infected machine) and the event log.

[TTS]

I have set up a test environment with only MX 100, Windows DHCP server, standard switch, and credit card machine. It seems to be working without any issues at all with new firmware. 

I updated my production MX again to latest firmware (15.21) last week. Then the issue started again 2 days after. Have support on the line when it happened but couldn't find anything.  Not only crashing all credit card machines, but it is causing network intermittent issue such as slow printing and connection unstable to most of the servers. 

The support asked me to do port mirroring on the switch that is connected to one of the credit card machines so I can do packet capturing using wireshark. Once I rolled back the firmware to 13.36, everything is back to normal.  

Any idea how to address this issue to Meraki with priority?