EEA Family Member - Divorce and Right of Residence

[victoria13]

Hi ,
I search every topic related to my problem but couldn't find any answer. So...
Non- eea national married to eea national for period of 3,5 years. ( 11/2010 )
Eea national worked on and off during marriage and for whole period of divorce proceedings. - exercising treaty rights at this time.
Decree absolute recived : 01/09/2014
Non eea applied for ROR and received new residence card for 5 years which expired 10/2020, but did not recieve letter of confirmation his ROR. (?????????)
Now my question is: when he will be able to apply for PR?
Is it 5 years from receiving decree absolute or he can apply earlier with ROR + 2 years exercising treaty rights independently?
My issue is lack of evidence of treaty rights from his ex before divorce proceedings.
Should we contact HO to request letter of confirmation???
Hope anyone can help
Thanks