I look forward to seeing your video. Be sure you record the combat log and make it large enough to read. That is because you may have turned off on-screen displays but the combat log will tell when you are hit and when you are missed.
Until then here is the evidence that AC works.
AC, fortification and PRR numbers.
Breakdown of AC numbers and also dodge %.
Combat log. Arrows for reference showing top of log and last entry to tie into next photo in case someone feels need to accuse me of altering the data.
One attack and hit.
Attacks two and three; 1 hit & 1 miss.
Attacks four, five and six; 2 hits & 1 miss.
Attacks seven thru eleven; 2 hits and 3 misses (2 due to dodge).
Total is 11 attacks with 6 hits, 5 misses (3 due to AC, 2 due to dodge). AC provides 60% of the misses, dodge 40% of the misses. Rest of the data calculations appear in a post above regarding what this means in terms of the Cloven-Jaw Warlord's actual to-hit number.
If you even have a 170AC character it is not getting hit every time. You might think it is if you are depending on what you see on the screen for your information. But, the combat log will tell the real story.
In this case the combat log clearly shows that dodge and AC give just under 50% protection against being hit -- and that with AC far below the 170 that you are claiming.
BTW, anyone else noticing that the AC value is growing in the troll's posts?