I am trying to figure out why the Intel wifi firmware occasionally crashes since 11n Tx aggregation was implemented for the iwm driver in #OpenBSD -current. If you want to help out please try this patch which is based on the best guess I've come up with so far:
https://marc.info/?l=openbsd-bugs&m=162038756305117&w=2
@stsp haven't seen the issue yet but I tried the Tx aggregation only very briefly, I'll check this out