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?  ... View more

I realize I am late to this post and am sure you have already found the solution to your problem.  I thought I would comment since I came across this post while I was troubleshooting roaming issues in a warehouse as well.  Hopefully somebody finds this useful.  Our organization is new to Meraki and we recently deployed 23 Meraki access points (MR53E) in a warehouse and started noticing that clients would connect to only certain access points which in some cases were too far away. This was causing many disconnects and frustration for the guys on the forklifts while using their scan guns.  We are using 5 GHZ in our deployment.  In the end we found out that the scan gun devices were not capable of using all of the 5 GHZ channels we had the access points using at the time.  We had to limit our access point to using only UNII-1 and UNII-3 channels.  This resolved the issue in our case.     ... View more