Minimum stay in the UK to maintain ILR status?

I have tried to find the answer to this question, searching the Home Office website, but no luck.
I am hoping that someone here will know.

For a person who has ILR in the UK and then returns to the Philippinnes for a long period (more than a year).........
1. How long can they stay out of the UK and still retain their ILR?
2. When they do return to the UK, what is the minimum stay in the UK that will maintain their ILR status?

Thank you!

https://www.gov.uk/government/publi...thout-losing-their-indefinite-leave-to-remain

Long periods out the UK may well affect a Citizenship application.

Thank you.
That seems to clear up the first of the 2 questions.