I think I would take the 'Noland' surname popping up in your US matches as being significant - it isn't a long leap from Nolan. (I have ancestors who arrived in 18C America from Germany with the name 'Knisely'; some of their descendents are 'Nicely').
Ethnicity from Ancestry tests is not of course wholly reliable, but if your matches have up to 20% Irish
shown in their results, I wouldn't dismiss that as insignificant. My mother's 3xgreat grandfather was an Irishman from Dublin, born of Irish parents - Ancestry doesn't give her any Irish ethnicity at all. My husband's 2xgreat grandfather was also Irish - Ancestry gives him 4% Irish ethnicity.
Not too sure I would place much faith in Ancestry ethnicity results as think they are based on tree matches.
Taking my closest matches of the group ;
49cM shared over 1 segment ; ethnicity result is 3%Irish,39% Scotland ,36% England ,12% Wales ,3% Norway .
45cM over 1 segment ;ethnicity result is 2% Irish,30% Scotland ,27% England ,18% Wales ,2% Norway
45cM over 1 segment ; ethnicity result is 15% Irish ,31% Scotland, 46% England ,7% Wales .
My own test shows as 97% Irish and 3% Scotland.
Went back for another look and looked at names/surnames in trees where available.
No recognisable "Irish " surnames at all as far as I could see.
Even the christian names are real Southern USA ones to my eyes , eg,Rufus ,Robert Lee ,Zelica ,Virgil Lee ,Erasberry ,Reuben Pickett etc.