New user - mobile detection problem

Hi,
I'm trying to setup Mobile Joomla! on a website and I have it installed and it works if I visit the site with ?device=auto on the URL but not if I just visit the site.
I've tried it in a new browser, private mode, cleared cookies etc. Am I missing something basic and obvious?
Many thanks.

What is URL of your website?
Do you use a caching plugin (Joomla's System Cache or 3rdparty one)?

Hi, thanks for the quick reply!
It's hullcommunitychurch.com
The System Cache is set to off in Global Configuration. The website is behind Cloudflare.

I guess it is a result of aggressive caching by CloudFlare, because on some device I got mobile version, and on others I got desktop version, but after clearing cookies and reloading page it switched to mobile version.

Could you send me (support​@​mobilejoomla.com) a list of CloudFlare's Speed and Caching settings you have enabled for your website? I'll try to reproduce it on a test website and found which one is responsive for incorrect behaviour.

Also you may try to set "Vary header" settings in the Mobile's Advanced settings. If CloudFlare takes it into account, mobile version of page shold be cached separately of desktop version.

Thanks for the information.
The "Vary header" setting didn't work but the cache settings on Cloudflare did.
The cache on Cloudflare was set to 15 days! Once that was switched off it started working straight away.
Thanks for all your help.