I just received a response back from support. I find it hard to believe but wanted to check if it is true as my initial thoughts were "you can't be serious" I tried reproducing the environment again and I found that L3 roaming reduces the MTU from 1500 to 1448 and I confirmed this with Engineering aswell. So the reason why we were getting that error in your tests is because of the L3 Roaming enabled. If you change the L3 Roaming to make a part of the LAN you would be able to send pings without any issues. Let me know if there is a specific requirement for which you need it to be in L3 roaming mode. But the whole point of L3 Roaming is to have seamless handover between APs. Or do I need to change over to bridging mode to get this working. I've not seen any mention in any documents and the only place I have found that talks about the MTU limitation is on a Cisco forum: https://supportforums.cisco.com/t5/lan-switching-and-routing/3560x-mtus-and-icmp-unreachables/td-p/2996925 The issue is that packets are silently discarded with no notification back to the wireless client and never sent to the destination. I'm surprised this hasn't been noticed before. ... View more

We are using MR32s two APs in a single office running around 30 people. The APs themselves are 10 Meters apart and have a fairly even split of clients connected. It's completely Meraki here, MX84 -> MS220-24P -> APs plus a number of wired devices. So it really couldn't get any simpler. Plugging in a Cambium E500 in sorted the issue and I can clearly see that the packets over 1462 are received by the AP, but never forwarded to the switch when I did a tcpdump on the uplink port to the MX84. ... View more

Cheers, I spent an hour with Meraki support explaining it and they are off to test in the lab. Asked if I could get access to roll back but the engineer was very hesitant and said the latest was the best version to be on. So going to wait and see if he can duplicate the issue in their lab. All the tcpdumps in the world showing the issue only existing on the APs and not passing to the switches couldn't convince him to let me try rolling back the firmware. ... View more

Is there a way to roll back to 25.8 if it has been over 2 weeks as the Meraki portal doesn't allow rollback if it has been longer than 2 weeks? Is there a way to force the downgrade as I am not familiar with the Meraki product suite and it isn't clear there is a way to do it? ... View more

I am having a semi-similar issue which may indicate that I need to do the firmware upgrade to 25.10 as well.   Started at a new company where we are having an MTU issue where I can't have a packet size greater than 1462 over wireless. The easiest way to replicate this is using ping. If I use windows with a  "ping 8.8.8.8 -l 1420 -f" (as windows take the 42 bytes for the ICMP packet) and I get a response, but 1421 and I don't. After various tests I have isolated the issue to the wireless network as I don't get this issue over the Switch -> Router -> Internet and don't have this issue on other wireless networks so have ruled out my laptop.   Since the firmware was upgraded over 2 weeks ago I can't roll back but there has been various complaints of certain sites being unavailable and VPN connections not working "for the last month or so" which to me sounds rather coincidental.   Planning to take a non-Meraki AP onsite tomorrow and have that option to test, plus upgrade to 25.10 when I have a failback position with a secondary AP as the site principally uses wireless for all devices and there is only two APs. ... View more