Meraki SD-WAN Security Appliance Firmware Update Web Site Speed Problem 17.10.2

[CyberDingo]

When I update the firmware of my Meraki MX100 SD-WAN Security Appliance from it's current version of MX 16.16.9 to 17.10.2 it seems to work fine, except for this strange issue. Any web search for a new website takes an unusually long time to reach. After the first time, however, any subsequent loading of the web site (or any site within the web site's domain) runs at normal loading speeds. I assume this is due to DNS caching. 

I have tried updating to 17.10.4 and have experienced the same issues. 

When calling Meraki tech support, they recommended me rolling back to 16.16.9 (which is what it is currently at).

Has anyone else experienced this issue, and/or has found a solution to this?

[PhilipDAth]

I have seen this issue on MX64s as well.  It doesn't seem to affect everyone.

I suspect if you do nothing (but stay on 16.x for the moment), a future upgrade will sort this out.

[cmr]

One possible fix, reported elsewhere on this community is to check that web cache is disabled as below:

[CyberDingo]

Thank you for the recommendation. I tried disabling Web Cache and it still shows the same problem. 
After scouring this community page, I think the problem shows itself when the Meraki passes to a L3 device within the LAN.

In my case it is a L3 Switch, but I have seen others say they have the same problem with a L3 VPN Concentrator.  

As of version 18.107.2 the problem persists. I hope Meraki can address this issue.