Hi,
We have offices in London, Hong Kong and Shanghai and definitely have issues with our MX64W in Shanghai.
I see registry issues with the VPN, sometimes it drops the connection, other times it stays up and the registry issue resolves itself. When the VPN drops for more than 5 minutes we usually reboot the appliance, which forces it to use another random port which seems to work. IIRC this was the advice of the Meraki Support rep. We live with this.
Out SH office is just a room in a managed service building, so we have no control over the internet connection or ISP provided to that office. It's literally just a cable hanging out the wall. I have no idea what upstream devices are being used, how the bandwidth is managed, whether any shaping is going on, etc. I have suspected this setup could be part of the issue, but we don't have another mainland Chinese office to test from.
The VPN between HK and London is rock solid.