My advice is to use 7Z program Free not winrar as the download passes crc therfore it may be winrar's fault I used to use it gave up about 5 years ago after it faile lots of crc on good files
Do a Cyclic redundancy check using
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on your compressed file see if it passes then you will know if its winrar
But NOPY is fine if its not for you you were unlucky servers do drop packets especially if your ISP is throttling file servers
Can cause file corruption hope this helps
My English is what it is