You can try other API servers but if you get the same error on a few of them it is most likely your clock.. (the clock on your phone should be accurate you might want to check it against your computer first before attempting to change the time - if you need to change the time you can do it manually you don't need to download anything, if you use windows you just right click on the time and select 'adjust date and time')
The other option is i jumped to conclusions and it is not the error i am thinking of. if your time looks fine maybe you can get a screenshot of the error?
the time is exactly the same on my phone to the second