Instead of 27.H11 a more crucial line is |27.r17. This has the effect of connecting white's central group to the bottom with either P21 or K18, and at the same time assists with a white attack to the top with R9. Play might continue 28.i11 29.r9 30.p9 and now here are two branches to demonstrate the complexity of this position.
31.t10 32.q9 (black's only move) 33.p8 34.r11 35.q10 36.p10 37.m10 38.o11 39.s13 40.r15 41.s15 42.v13 or 37.m9 38.l9 39.o9 40.n9
31.q11 32.r5 33.q7 34.o6 35.r6 36.s7 37.q4 38.p5 39.o5 40.q6 41.p7 42.p8 or 39.p6 40.o7 41.s8 42.q3 43.t6 44.t4

Of course, I could have missed something.
17.L11 was very tempting but it has a weakness on the right side which I took advantage of. Instead, |17.p13 looks much stronger for you, threatening either L11 or R9 to reach the top, and preventing my S21 threat.