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I did it via an X wing on 6s, followed shortly afterwards by an XY wing 279
making r3c3 6 and stte

only fundamentals needed - and even draw/play played elementary moves until it changed rating from v hard to hard!!

I did this twice to check it needed fundamental only

I did it once with nothing but fundamentals - thought I had made a lucky mistake so did it again with nothng but fundamentals

so why? why?

Mea Culpa I did make the same unjustified entry twice ...

The 356 is exactly the same as clement's except it can be extended since if r4c6 is 6 then r2c4 is 6 so the xy wing (with extension) takes out all the 6 in col4 of box 2

356 and the result of the extension is exactly the same as Clement's solution
since the 6''s confined to col 5 in box 8 give the same solution i.e r3c5=9

Your use of the wing Clement sets r9c6 to not 6 But the wing at r4c6 can be extended (by 56s) to r2c4 so r3c5 becomes 9 and thereafter solution is easy

Don't know why no postings until today BUT
XY 467 pivoted at r4c5 so r2c4 not 4 so 3

Marty
I did it by noting the 3 connected 37, so if the one at r2c3 is 7 then r6c8 is also 7 and block 3 has nowhere for a 7 so r2c3 must be 3 stte

I'm getting senile. I thought I posted last night but I don't see it.
W-Wing (79) in b26, SL 9 in c7, with pincer transport=> -7r2c3.

+------------+--------------+--------------+
| 2 3 4 ...

[code]
+---------------+----------------+---------------+
| 2 3 469 | 45689 489 4589 | 7 489 1 |
| 67 8 4679 | 1 2 479 | 349 5 39 |
| 17 147 5 | 3 489 4789 | 6 ...

A 4 in r1c3 immediately leads to a 4 in r2c8 which leaves row 5 destitute of 4s! so r1c3 cannot be 4 ...ste

tyhe xyz wing 457 r2c5 andr9c56 takes out the 5s in c5r78 So r9c2 becomes 4 ...ste

perhaps once again the software may have used an Xwing in 4s col 5 and 7 which is so obvious that it hardly counts as an advanced move. OK I am not sure whether it is needed to solve the puzzle

If r3c9 is not 4 we immediately get two 1s in block 1 so r3c9 must be 4 and this solves the puzzle

Sorry I got it wrong I meant r1c8 not r1c7 for one wing that becomes 2 if r6c8 is 8 whilst if r6c8 is 7 then r6c3 becomes 29 so that is equivalen to a wing being 2 since it denies a 2 o r1c3

The pivot at r6c8 denies a 2 to r1c3 either via r1c8 or the pair of 29 at r56c3 so it is a kind of xy wing according to its mechanics but not apure XY I wonder what it is called a compound XY wing?

Can't imagine that you of all people missed the XY wing 367 pivot r4c1

Surprised nobody contributed yet

I could only find a W Wing 12 operating on 2s in col 2 so r3c1 becomes 1 stte

Looking again I find that the W Wing is available immediately and sets r3c1 to 1 wh ...

Xwing on 5 cols 5,9 opens up xy wing 567 pivot r4c9 so r5c7 is 7 stte