yii2mod/yii2-timezone: not working with Firefox and Internet Explorer

My timezone is :

Africa/Nairobi

, chrome and opera give that timezone(it works very very well) but firefox and explorer(edge) give :

America/Denver

I tried to post the issue on github (https://github.com/yii2mod/yii2-timezone/issues/2), it seems there is not solution.

So Is there any other Yii2 client timezone detector extension that I can use? If there is know extension is there any other way I can get it ?

Is there any idea on how I can solve this?