Code:
SELECT * FROM Posts
WHERE User = 'admin'
AND Number >= ( SELECT Number FROM POSTS WHERE POST = 'soctqr26i7aycza2u73pi')
ORDER BY Number
LIMIT 25
???
It would have helped if you have shown the field names for each of those columns. And/or if you had used
SELECT field1, field2, field3, ... instead of
SELECT * (which you shouldn't use, if possible).