I am totally lost, can anyone help please ?

[a-l]

My test was done with 23and me, where I found an unknown first Cousin in my search for my Grandfather.
The problem is how we are related.
It has to be an illegitimate birth but who the parents and child were , we are stuck.

We both link to somebody who has the surname of my supposed Grandfather in his family. The link is 4.2 generations which I don't understand.

Another thing is that my new found Cousin wasn't aware of any English ancestry, hers is Polish and German.

Our link is 11.09 per cent DNA.
Largest segment 85.3 and total segments 817.8.

My link to the person with the supposed Grandfather's surname is
Largest segment 24.5 and total segments 40.1.

I'll be very grateful if somebody can give me some ideas please.

[hurworth]

The shared DNA would fit with being first cousins, but other relationships are possible such as half aunt or uncle, or half niece or nephew for example.

23andMe seems to focus more on health than genealogy, so you may want to consider uploading elsewhere, such as FamilyTreeDNA, MyHeritage and Gedmatch.

What gender are you and your match?  Does 23andMe include information about the X-chromosome, and if so, are you matching each other?

Are you getting "expected" matches from your paternal and maternal sides?

[a-l]

Thank you for replying.
We have both uploaded to Gedmatch and Ftdna and we are both female.
We don't connect on a female link.

Our connecting link is male. This is the only link we have.
Her family names are Polish and German of which I have none. She has no English names in her family.

[a-l]

A big thank you hurworth for all of your help.

[JohnDoe2020]

That range of match can be several relationships. Go to the shared cm project on dna painter. Free. Plug in the CM and it will provide probabilities of relationships. Relationships are influenced by generations. Are you two a similar age? While she may not be aware of English roots, you may not be aware of polish or german. Ethnicity is flexible and based moremon community...

[a-l]

Thank you very much for your help, I will try that.