Three separate triples horizontally and vertically.
Prelims
a) R12C4 = {59/68}
b) R2C56 = {12}
c) R4C89 = {29/38/47/56}, no 1
d) R5C34 = {15/24}
e) R7C23 = {29/38/47/56}, no 1
f) R7C67 = {59/68}
g) 22(3) cage at R1C3 = {589/679}
h) 11(3) cage at R4C6 = {128/137/146/236/245}, no 9
1a. 22(3) cage at R1C3 = {589/679} -> 5,8,9 or 6,7,9 must be one of the vertical triplets
1b. R12C4 = {59} (cannot be {68} because vertical triplets only contain one of 6,8), locked for C4 and N2, clean-up: no 1 in R5C3
1c. 5,8,9 must be one of the vertical triplets -> R3C4 = 8, 22(3) cage = {589}, locked for C3 and N1, clean-up: no 1 in R5C4, no 2,3,6 in R7C2
1d. Naked pair {24} in R5C34, locked for R5
2a. Naked pair {12} in R2C56, locked for R2 and N2
2b. 11(3) cage at R4C6 = {137/146/236} (cannot be {128} which clashes with R2C6, cannot be {245} which clashes with R5C4), no 5,8
2c. Killer pair 1,2 in R2C6 and 11(3) cage, locked for C6
2d. R456C5 = {589} (hidden triple in N5), locked for C5
2e. R789C6 = {589} (hidden triple in C6), clean-up: no 8 in R7C7
2f. R7C23 = {47}/[83/92] (cannot be [56] which clashes with R7C67), no 5 in R7C2, no 6 in R7C3
3a. Hidden killer pair 5,9 in R3C3 and 12(3) cage at R3C7, R3C3 = {59} -> 12(3) cage must contain one of 5,9 = {129/156/345}, no 7
3b. Horizontal triplets must contain both of 1,2 -> 12(3) cage = {129/345}, no 6
3c. Consider combinations for 12(3) cage
12(3) cage = {129}
or 12(3) cage = {345} => R3C12 = {12} (hidden pair in R3), R3C3 = 9
-> 1,2,9 must be one of the horizontal triplets, totalling 12
3d. R2C56 = {12} -> R2C4 = 9, R1C4 = 5
3e. 16(3) cage at R9C4 doesn’t total 12 -> doesn’t contain 1,2,9 = {457} (cannot be {358} because 5,8 only in R9C6, cannot be {367} because R9C6 must contain one of 5,8) -> R9C6 = 5, R9C45 = {47}, clean-up: no 9 in R7C7
3f. 4,5,7 must be one of the horizontal triplets, R1C4 = 5 -> R1C56 = {47}, locked for R1 and N2
3g. The other horizontal triplet must be 3,6,8
3h. Naked pair {36} in R3C56, locked for R3
3i. 12(3) cage = {129}, locked for R3 and N3
3j. 22(3) cage at R1C3 = [985] -> R1C12 = {12}, R2C12 = {36}, R2C789 = {457}
3k. R7C67 are in different triplets -> R7C67 = [95] (cannot be [86] because 6,8 are in the same horizontal triplet)
3l. R7C6 = 9 -> R7C45 = {12}, locked for R7 and N8
3m. R7C7 = 5 -> R7C89 = {47}, locked for R7 and N9 -> R7C123 = [683] -> R2C12 = [36]
3n. R8C6 = 8, R8C45 = {36}, locked for R8
3o. Naked triple {129} in R8C789, locked for R8 and N9
3p. 17(3) cage at R6C1 = {368} (the only horizontal triplet totalling 17) = [836]
3q. 11(3) cage at R4C6 (step 2b) = {137/146} (cannot be {236} which clashes with R3C6), 1 locked for C6 -> R2C56 = [12], R8C45 = [12]
3r. R7C7 = 5 -> R89C7 = [98] (vertical triplet 5,8,9)
3s. The remaining vertical triplets total 11 and 12 with 2 in the 12 -> R8C9 = 2, R8C8 = 1, clean-up: no 9 in R4C8
3t. R789C3 must total 11 or 12, R7C3 = 3, R9C3 = {12} -> R8C3 = 7
3u. R6C1 = 8 -> R45C1 = {59} (vertical triplet 5,8,9), locked for C1 and N4 -> R8C12 = [45], R3C12 = [74]
4a. R5C789 = {368} (horizontal triplet 3,6,8, cannot be in R5C456 because R5C4 only contains 2,4), locked for N6, 3,6 locked for R5, clean-up: no 5 in R4C89
4b. 5 in N6 only in R6C89 -> R6C789 = {457} (horizontal triplet 4,5,7), locked for R6, 4,7 locked for N6
4c. R56C6 = [71] -> R4C6 = 3 (cage total)
4d. The remaining vertical triplets must be 1,3,7 and 2,4,6
4e. 12(3) cage at R7C9 = [426]
4f. R4C9 = 9 -> R56C9 = [85] (vertical triplet 5,8,9)
and the rest is naked singles.