Robert I'ans who was Master of Ordnance under Queen Elizabeth was actually Robert J'ans or Janes (see Burke's peerage) "Janes, or Janns (James Janes, Mayor of Dublin, 1593, son of Robert Janes, or Janns, Master of the Ordnance in Ireland, 1559. Visit. city of Dublin, 1607). Gu. on a bend ar. three Cornish choughs sa. beaked and legged of the first." No "Sir" in any of the documents available online.
His name was sometimes given as Yans in the early days, but I have not seen it as I'ans in the early records (although he did answer to Delman or Dellman). He was not Welsh. According to authors of The Origins of Sectarianism in Early Modern Ireland he was born in Kent, though he made his mark in Ireland and never returned to England.
The only sons on record for him are Thomas and James. The earliest records I have seen for him date to circa 1535 when he was receiver of customs for Drogheda. He was bailiff and sheriff of Dublin circa 1547, which seems to be the about last time he is on record. His son James was mayor of Dublin in 1593 and died in 1620 (according to the memoirs the family of his 3rd wife, Mary Carus, who survived him).
In spite of the occasional use of "Yans" for Robert's surname, it seems unlikely he has any connection with the Iiams family.