This may be related: em(4) interface hangs randomly, receive buffer full (Intel i210) https://marc.info/?l=openbsd-misc&m=145696725605233&w=2
I've been having those Tor hangs for months. The same issue, clock skips ahead some minutes and breaks Tor connections but not clearnet. They happen quite frequently, at least three times a week to say. Heck, I've seen this issue for more than a year since OpenBSD 5.6 or 5.7. The issue became worse late OpenBSD 5.8. It seems like the issue gets worse when Tor's HardwareAccel option is enabled (HardwareAccel 1). Disabling it has helped a lot, but hasn't resolved the issue. I've also never been able to get more than ~1 MB/s throughput for some reason with or without HardwareAccel on OpenBSD. No idea why, probably the constantly breaking circuits. I spent 2.5 months debugging the issue and it's still persisting. I've posted a full email transcript with more details.[1] It seems to be a little random which Tor connections get dropped. There are IRC users connecting to an .onion address, and for years only some of them have dropped connections and some kept going. This server also uses OpenNTPD for syncing the clock from NTP.org Sweden pool. I haven't tried disabling it yet to see what would happen. [1]: https://partyvan.eu/transparency/emails/2016-02-16-portlane-nic-downtime.txt
