Does the time difference between Dublin and Lagos change during the year?

Yes. Because of daylight saving time the gap moves between −1h and 0.

When is the best time to call Lagos from Dublin?

Between 09:00 and 17:00 in Dublin, which is 09:00 to 17:00 in Lagos.

Dublin and Lagos are on the same local time. This gap is not fixed: daylight saving time moves it between −1h and 0 during the year.

Dublin

Ireland

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Lagos

Nigeria

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A 9-to-5 day in each city overlaps for 8h. That is 09:00–17:00 in Dublin, which is 09:00–17:00 in Lagos.

City	Time zone	UTC offset
Dublin · Ireland	Europe/Dublin	UTC+1
Lagos · Nigeria	Africa/Lagos	UTC+1

What is the time difference between Dublin and Lagos?: Dublin and Lagos are on the same local time. This gap is not fixed: daylight saving time moves it between −1h and 0 during the year.
Does the time difference between Dublin and Lagos change during the year?: Yes. Because of daylight saving time the gap moves between −1h and 0.
When is the best time to call Lagos from Dublin?: Between 09:00 and 17:00 in Dublin, which is 09:00 to 17:00 in Lagos.