MR-76 PSK SSID - Zebra MC9300 dropouts and slow reconnect

[replicant]

I have a warehouse with 7 MR-76s deployed at a height below 9.5m and positioned vertically. The Zebra MC9300 prefers the 5GHz broadcast of the PSK SSID used solely for the RF scanners. There are 3  RF scanners onsite. All guns have challenges across a string of APs that follow an aisle path. No interference is noted from the RF Spectrum tool within the dashboard for 5GHz. Heatmap displays adequate coverage for the aisle path. The older Cisco APs did not have trouble with an older model Zebra gun prior to replacement of both AP and RF scanners. The RF scanners are all on the same revision of firmware as a set of guns in a different warehouse. The RF scanners in the other warehouse do not have the consistent disconnects and use the same PSK.

My next step is to retrieve logs from WiFi Analyzer in the Zebra toolkit; however, I wanted to ask about other Community members' questions regarding the Zebra RF MC9300 scanners and their behavior in warehouse environments.

Additionally, 20MHz channels for the 5GHz spectrum are allocated. No channel overlap or interference noted. Basic Outdoor Radio Profile. All APs have similar range Tx power.

[Ryan_Miles]

When you say "The RF scanners in the other warehouse do not have the consistent disconnects and use the same PSK." are those the same model APs and scanners? And if yes, is there a config difference between those APs are your problematic warehouse site?

[replicant]

AP model of MR-76 is the same in both warehouses. Same RF scanners in both warehouses. Same Radio Profile for MR-76s in both locations. 

[replicant]

This has been an arduous journey that's not quite over yet. I think there is something to still be done within the Zebra scanner that I haven't touched upon yet.

Meraki MR-76s running 28.6 in all warehouses. Band steering turned off. SSID for scanners only announced on 2.4GHz. No visible interference in RF spectrum. Channel usage for 2.4GHz always in 'Acceptable' range. Minimum bitrate reduced to 6Mbit for this SSID. Transmit power for these MR-76s Radio Profile expanded to 20dBm for 2.4GHz.

Warehouse 1 -

• All Zebra MC9300s are Android 10, not fully patched beyond patch revision 70.
• All Zebra MC9300s are using same TE application and version
• All Zebra MC9300s have WiFi profile deprecated to see only 2.4GHz
• All Zebra MC9300s have WiFi 'Never Sleep' applied through StageNow

Warehouse 2

• All Zebra MC9300s are on Android 8, never patched after purchase
• All Zebra MC9300s have same version of TE application
• All Zebra MC9300s have WiFi profile deprecated to see only 2.4GHz
• All Zebra MC9300s have WiFi 'Never Sleep' applied through StageNow

The dropout rate has remained very painful for both warehouses' shipping staff. 

In most all the cases where a scanner has dropped its session with the host destination in the TE application, the device remains pingable from the AP. Around 80% of the time, the device is pingable from other locations in the networks on different segments that allow two-way conversations and don't have firewalls between.

It's as though the device's application suite has one application go dormant and then stifles all the remaining tools. And, that application isn't the one that's being used to access order fulfillment via the TE.

If anyone has insights about what additional factors in the Meraki's Radio Settings that could be manipulated, I would greatly appreciate it.

[replicant]

SOLVED: The root cause of this issue was roaming. Though the MR-76s replaced APs in a location throughout the warehouses, it was roaming between APs and how the auth between MR and MC9300 agreed to disagree. 

Solution was to deploy most recent Android OS patching, Zebra firmware updates, and terminal emulator client. Roaming occurs more easily. Client device recovers automatically, only sometime breaking terminal emulator session.

[TomasB]

Can you define what Android OS version had this issue?

[replicant]

Zebra MC9300 on Android 8.1 (Security Patch Level January 2021) or Android 10.0 (patch revision 70 - Security Patch Level April 2021)