DBCC CHECKDB fails after restore to SQL Server 2017
You can find out what object(s) those pages belong to by running:

SELECT s.name, o.name, a.index_id
FROM sys.schemas AS s
INNER JOIN sys.objects AS o
ON s.[schema_id] = o.[schema_id]
CROSS APPLY sys.dm_db_database_page_allocations
  (DB_ID(N'DBNAME'),o.[object_id],NULL,NULL,N'LIMITED') AS a
WHERE allocated_page_page_id BETWEEN 1737 AND 1743;


You can try rebuilding that index (or table if index_id is 0 or null) to see if that fixes the allocation problem. If it remains, you could try dropping the index and re-creating it or, again, if it is a table or heap, selecting everything into a new table, creating the new indexes there, dropping the old table, and renaming the new one.

If that doesn't help, you can inspect the contents of those pages, and determine if it is acceptable to lose the data as a part of your upgrade (or, if not, to not upgrade).

DBCC TRACEON(3604,-1);
DBCC PAGE(N'DBNAME', 1, 1737, 2);
DBCC PAGE(N'DBNAME', 1, 1738, 2);
DBCC PAGE(N'DBNAME', 1, 1739, 2);
...


If it is an acceptable loss then you can run the repair with allow data loss as suggested (it might be smart to keep a copy of the backup before repairing in case you ever need to pull the data from those pages in some way).