1) The expiry date of the product will be 1 year from the date stated on the label, unless otherwise advised by the supplier.

OR

2) The expiry date of the product will be 1 year from the date stated on the label, unless advised otherwise by the supplier.

Which is correct?

Neither is correct. The word is "expiration" not "expiry."

If you're asking about the word order after the comma, it doesn't really matter.

Hmmm. I guess it's different in Canada: http://www.justice.gc.ca/eng/dept-min/pub/legis/n13.html

The word order still doesn't make any difference.

Both sentences are correct, but they have slight differences in terms of word order and punctuation.

1) "The expiry date of the product will be 1 year from the date stated on the label, unless otherwise advised by the supplier."

In this sentence, "unless otherwise advised by the supplier" is positioned at the end of the sentence, separated by a comma. This phrase adds additional information to the main clause about the possibility of the expiry date being different if advised by the supplier.

2) "The expiry date of the product will be 1 year from the date stated on the label, unless advised otherwise by the supplier."

In this sentence, "unless advised otherwise by the supplier" is placed directly after the word "unless," without any additional punctuation. This phrase conveys the same meaning as in the first sentence, indicating that the expiry date may be different if the supplier advises otherwise.

Both variations are grammatically correct and convey the same meaning. The choice between them may depend on the desired emphasis or style of writing.