How does this work then?
 

OH has had a DNA test done and so has his daughter.

OH has a DNA match with a person and these are the details given by Ancestry:

Possible range: 4th - 6th cousins
Confidence: Very High
Shared DNA: 59 cM across 5 segments

This is the result for his daughter with the same person:

Possible range: 3rd - 4th cousins
Confidence: Extremely High
Shared DNA: 93 cM across 6 segments

So, she is more related to this other guy than her father is??

*scratches head*

Could be that she is related to that person on both sides? Or it is just a statistical error.

I think it's very unlikely there's two connections (and OH would be horrified at the thought lol).

Also, if there was a relationship on both sides, wouldn't there be a likelihood of there being other people who would show a link in a similar way? I can't see any others.

A statistical error is boring though! lol

I've a few similar, although lower amounts, with my father's results. Been scratching my head a little, especially when there is only a single segment match and my cM is higher.

have a look at the shared matches for both OH and his daughter and see if that helps.

From what I understand the only way to know for sure what is happening is to upload the data to another website that lets you look at the actual segments and hope that match is also there.

There are about 3 different types of DNA matches, firstly a match as you are actually related, the other 2 confuse me but are basically flukes and you aren't related at all. However ancestry apparently cuts the segments off so it might just be that OHs were chopped differently to his daughter. I really don't understand it all but she might have one or more segments that aren't a relationship and the others were cropped too much for OH.

There is a FB group that is very knowledgable but they are mainly US people (if that is an issue for you) and they will recommend using GEDMatch to look at each segment to work it out for sure.

Thank you all.

Toni, I will suggest he has a go at uploading the two sets of results to GEDMatch and see what happens. I will report back!

Another thing I've just noticed - Both our children (ie half siblings of OH's daughter in post #1) have done DNA tests, but neither of them have this man (with the details in post #1 above) in their list of matches. Odd?

Make sure to read all the privacy info about GEDMatch first!
I don't think it's unusual for the (other) children not to have inherited that amount of shared DNA.

That is curious I would expect similar to OH or less because otherwise to me it looks like it has jumped a generation. Although it isn't a great difference perhaps the methodology has gone a bit awry.

Not necessarily, because it wouldn't mean that your OH and his ex are related to each other, just that someone is distantly related to both of them.