Islamically, you are not allowed to abandon prayers with the congregation on the account that your clock’s calculation says differently. You have to try and find the time of prayers through observing the sun. if this is not possible, you have to pray with the Muslims.

And Allah knows best

I am always in a dilemma when I go for vacation. The timings of prayers especially ZUHR and ASR is delayed by at least one hour. I had a software loaded in my mobile and it calculates the timings as per Saudi system.During these paryers there is always a difference on at least one hour i.e ZUHRis at 2 pm and ASR is at 5pm. Now in situations like this is it necessary to pray alone at home at their early stated timings or pray with Jamaat at late timings. Only a few Masjids follow the prayers at their early stated timings.