Synonyms of 'wander off something'
▷ See wander
He has a tendency to wander off the point when he's talking.
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To deviate from something means to start doing something different or not planned, especially in a way that causes problems for others.
He didn't deviate from his schedule.
If you digress, you move away from the subject you are talking or writing about and talk or write about something different for a while.
She digressed from the matter under discussion.
Thesaurus for wander off something from the Collins English Thesaurus