I have a couple of tests, which I run them on windows and I have a successful run.
But when I move to UBUNTU server with Xvfb, I faced problem with tests, some of them failed!!

both cases I used:

 - Maven 3.1
 - Selenide v3.5 
 - Selenium v2.53 
 - Firefox v45.0.1


So from where these problems? is it related to Firefox version? or I have to modify in the code somewhere? 

some of them can't run:
>org.openqa.selenium.firefox.NotConnectedException: Unable to connect to host 127.0.0.1 on port 7055 after 45000 ms. Firefox console output:

and others can't find elements while executing.