For two males to be related by YDNA, both males must be from the same YDNA Haplogroup as shown on the pie chart above. This Boyt YDNA happens to be a rare Hap H. The Boyd lines of Scotland are the more common Hap R and I. No Hap H Boyd's have been found in the UK from living males or grave remains that match Boyt. Generally speaking you will not find BOYD families in Ireland during the Medieval Period. BOYD first arrives from Scotland about 1610. BOYT arrived much earlier, by matching 2 sets of male YDNA from Ancient Bones discovered south of Dublin and the first record of a Thomas Boyt is in 1237 residing in Drogheda, but detained with associates in Bristol until released by the King.

More Detailed:

AI Overview, BOYD
Boyd is primarily an ancient Scottish surname derived from the Gaelic word buidhe (meaning "fair" or "yellow-haired"). The first Boyds to settle in Ireland arrived in the early 1600s as part of the Plantation of Ulster.Notable first appearances and records include: The 1610 Ulster Plantation: Sir Thomas Boyd (son of the 6th Lord Boyd of Kilmarnock, Scotland) received an official Crown grant of \(1,500\) acres in County Tyrone, Ireland on August 29, 1610.

Widespread Settlement (1680s–1700s): Large waves of Scottish Boyds migrated to Northern Ireland (particularly Counties Antrim, Down, and Londonderry) between \(1680\) and \(1688\). From these regions, many descendants subsequently sailed to America in the 1700s. To explore the earliest lineages and detailed genealogical trees of these early Ulster-Scot families, consult the ireland - RootsWeb database or reference the History of the Boyd Family and Descendants archives.

AI Overview, BOYT
Yes, the surname Boyt is strongly associated with medieval Anglo-Norman and Scottish origins, and has been documented in Ireland as early as the 13th century. Origins and Etymology While often considered an early variant of the Scottish surname Boyd, the etymology of Boyt points to both Norman-French and Gaelic roots:Norman-French:

Some historians suggest the name derives from buidhe, an old French-influenced iteration of the Gaelic word for "fair" or "yellow(-haired)", or from the French word boite (box). Habitational: Others suggest the name is a variation of Boid, derived from the Gaelic name for the Isle of Bute (Bòid) in Scotland. Medieval Dates in Ireland The surname Boyt is surprisingly old in Ireland, predating much of the later Scottish plantation migrations. Medieval dates and references include:1237:

The name appears in the Calendar of Close Rolls (Henry III) dated July 22, 1237, which records a Thomas Boyt residing in Drogheda, Ireland.1312: Court records at Pleas of the Crown in Drogheda mention Thomas Boyt and Philip Boyt in County Meath.1313: Philip Boyt and Henry Boyt appear as jurors in trials in Meath.Anglo-Normans in IrelandThe Anglo-Normans first arrived in Ireland in 1169. During this era, many Normans intermarried with native Gaels or brought Anglo-Norman, Flemish, and Anglo-Saxon vassals, retainers, and merchants—such as the Boyts—with them into Ireland. Consequently, Boyt evolved as a distinct merchant and settler surname throughout the medieval period.

For further reading on the name's history and variant spellings, you can refer to historical profiles on the Boyt - Guild of One-Name Studies or the Boyt History portal.

Also see MED Timeline, including:
1374 Sir William Windsor, Standing Force France: Thomas BOYS, Archer 13740418
1374 Sir William Windsor, Standing Force Ireland: Ralph BOYT, Archer 13741018
1421 Woodville, Richard (the elder) (1385 - 1441), Standing Force Ireland: BOYT, Archer

https://pbase.com/daveb/med
BOYT TIMELINE IRELAND: 1237CE *************************

Actually it is fairly easy to see if you have a BOYD or BOYT male line in Ireland. First is the dates, as the first BOYD families in Ireland was about 1610CE, Ulster Plantation (Ulster-Scotts) migrations to the colonies begin in the 1700's The fist BOYT's in Ireland are Thomas Boyt already residing in Drogheda by 1237CE and another Thomas Boyt as paid archer in both Standing Armies of Ireland and France in 1374CE. The Boyt associates de Verdon,Verdun are known to be Knights of the King in Ireland and of Anglo-Norman Families. See complete MED Timeline in Ireland.

The second way to know is the YDNA BigY SNP results. The Boyd YDNA Surname Project has almost 500 tested members and not a single match from any Boyd lines. Thanks to the unique Hap H in all Boyt lines, matching only each other and ancient grave remains in pre-surname Ireland and France. In reviewing the Boyd YDNA they are mostly the common Hap R and I generally referenced as Anglo-Saxon and Viking as is most of the UK males.
https://www.familytreedna.com/public/boyddnanet?iframe=ydna-results-overview