Log in problem with mobile

I have no problem when I log in from my laptop with IE or Chrome.
However I cannot log in to forum with my mobile using chrome browser.
I tested with an iphone in Safari. No problem logging in.

My phone is samsung s7. Does anyone have the same problem with me?

I tried with mobile and desktop site nothing changed.

It shows the welcome screen after entering user name and password but opens the log in page again. :wtf: