Router began studying for the priesthood at St Patrick's College, Maynooth, in 1982, completing a Bachelor of Divinity and a higher diploma in education.

Between 1991 and 1996 he taught English, geography and religion at St Patrick's College, Cavan, while also serving as chaplain and coaching basketball and Gaelic football.

[3] Router was appointed chaplain to Bailieborough Community School, where he also coached basketball and Gaelic football, and resident priest in Kilmainhamwood and Moybologue in 1996, before completing a Master of Religious Education at Mater Dei Institute of Education, Dublin, between 2002 and 2003, during which time he was assistant priest in Our Lady of Good Counsel parish, Drimnagh.

[4] Router returned to the Diocese of Kilmore in 2003, where he was appointed resident priest in Castletara (centred on Ballyhaise) and diocesan director of adult faith formation and pastoral renewal, where he was responsible for providing training, encouragement and support for parish pastoral councils, liturgy groups, Eucharistic ministers and Ministers of the Word.

It was during his time as diocesan director of adult faith formation and pastoral renewal that Router also wrote a religious affairs column for The Anglo-Celt and the Cavan Voice.