Wierd problem. Cant Post or even preview new posts

Hello

Having a super wierd problem. Whenever I try to a new post, after writing 1 or 2 l8nes, if I press preview or post, it works normally as it should… but if i make a normal post, and press preview, save OR publish… I am taken back to the main homepage…

Yes i have disabled ALL plugins, updated the simple theme but still the same problem. Even tried different browsers but same problem.

Then I installed just 1 plugin (https enforcer)… so that there is no confusion between https and http (I had tried to use both previously)… still didnt work

I can giv my username and pass to anyone to try it out

website URL is: howtoquitsmoking.xyz

regrds

p.s I am on a shared hosting.. PHP version 5.6