I have setup the hotspot, and it works really well for PCs and laptops, but no smartphones can see the logon page.
My login page has been modified to show some T&C, and then the user just clicks the I Accept button.
It works great for computers, but not smartphones.
Any ideas?
Smartphone browser problem . Try to change the browser . For me works great with Opera
That’s a monumental task when we have 800 guests a day through this wifi system. 
Is the hotspot page hosted on Mikrotik or external server?
Can you post the login page html?
Which smartphone OS has trouble?
I have many custom hotspot pages and smartphones work just fine.
Sir reverged
would you mind sharing some of your many custom hotspot pages? i would be happy to to use some of your and give credit to it..
Experience that I have met. Try to changing DNS name (for example .info)
Reference : http://forum.mikrotik.com/t/iphone-ios-v4-problem-with-hotspot-logon-page/38835/1