We recommend using Cloudflare as it offers free SSL and other services. If you choose this route, we even have a guide showing you how to set things up using Cloudflare.
Setting up a subdomain pointing at your myDevices app URL would normally result in an SSL warning when viewed by your customers.
There are two options available to solve this, and which you choose will guide your next steps.
There are a number of CDN providers out there that offer SSL termination.
Cloudflare (Recommended)
AWS Cloudfront
Rackspace
We recommend using Cloudflare as it offers free SSL and other services. If you choose this route, we even have a guide showing you how to set things up using Cloudflare.
Continue to use your current provider, but deploy a Load Balancer such as Nginx or HAProxy with your own certificate and proxy requests to your myDevices white label domain. This option requires more technical skill, but also offers flexibility.
If your provider does not support CDN or reverse proxy services, or if you are not able to configure deploy and configure a reverse proxy on your own, the easiest way to proceed is to utilize a free Cloudflare account.
We have a guide showing you how to accomplish this, using GoDaddy and Cloudflare as the examples.
Example: Using GoDaddy and Cloudflare