MR 45s randomly going offline from Meraki Dashboard

[RiderCoach2021]

We have over 400 MR 45s in residential dorms and we seem to have them randomly go offline.  Already attempted to research here as well as google and only found that IF using NAT with the SSIDs they will reboot every 4-hours, which we are not using.  Currently, the only option is to go to the physical location and unplug the network cable attached to the wall jack and then plug back in.  This allows a reboot and they reconnect to Meraki Dashboard.  This may or may not re-occur at that location from a few hours, days, weeks, months or year.  Again, it is randomly occurring.

Here is some general setup information:

We are using a layer 2 setup within each building with a layer 3 to branch back to our data center.  The internet is separate from the schools network and has a separate firewall,however, we are using DHCP for the IoTs to connect to the MR 45s.  Each DHCP block/range are specific to that building.

Any ideas/suggestions as to why this is occurring would be greatly appreciated.

[DarrenOC]

I'm assuming that the devices just lose connectivity to the cloud but whilst doing so do they remain operational and continue to serve clients?

Are these the only Meraki devices on your network?

Possible DHCP related issue?  Stale entries, scope not sufficient enough for the qty of AP's on the network?  By the time you get round to rebooting the device an IP address is freed up thus allowing the rebooted device to reconnect.

[DarrenOC]

Firmware version?

[RiderCoach2021]

Just had them all automatically updated/upgraded to MR 28.1.

However, I believe they were on 27.1 before the update/upgrade.

[RiderCoach2021]

Darren,

Answers to your questions:

1) Once connectivity to cloud is lost, they no longer serve our clients

2) Yes, these are the only Meraki devices on this network

3) Yes, we have checked/verified our scopes are sufficient enough to meet the quantity of our AP's on the network.