@AlexCol I have the same exact problem on a newly purchased X55 on firmware using OpenVPN Client, which is obviously broken and not being addressed. I should probably return to Amazon but as an IT Architect I'll give TP-LINK's Deco IT support a chance to correct it.  

I am using VPN Unlimited's Router Configuration file, which loads and works instantly with the OpenVPN Android client. As I want to place the entire network behind the VPN, either a software update to the Deco client or router firmware itself to fix this vitally important feature.