I have a similar problem to this except my machines are running macOS 10.14.4-10.15.1 (I am not running bootcamp) with MR34 APs on Meraki firmware 25.14. This occurs with 2018 13" MacBook Airs (MacBookAir8,1) on the AirPort Extreme (0x14E4, 0x843) wifi card with firmware 9.113.2.0.32.5.36 (macOS 10.15.1). The symptom seems to be that all of a sudden the device stops being able to access the Internet and/or Internet speed grinds to a complete halt. For example running the speed test on my.meraki.com while this is happening I see throughput at 0.24 Mbps whereas when things are working fine I am at 75 Mbps+. While the problematic client speed drops to 0 I am able to speed test on another laptop, connected to the same AP on the same 5Ghz radio and speed test at 75 Mbps+ at my.meraki.com. When the problematic client speed drops, I am still able to ping the AP, my local gateway, and Google DNS with very little latency and zero dropped packets from the problematic device.    As a test I created a new SSID and disabled the 5Ghz radio. I migrated the problematic client to this SSID and I have not had this problem reoccur. It seems to be related to the 5Ghz radio either on the Meraki side or on my Macs. I have expanded my test to a few more devices to see if this continues to "help" with the situation. I have a case open with Meraki on this and I will be opening one with Apple next week. ... View more