bumblebee with optirun/primusrun: timeout after ~ 1 minute

Question

I've successfully been using bumblebee with optirun/primusrun on my Optimus laptop for quite some time now. However, since yesterday, both programs suddenly hang without actually launching anything for about a minute. I did install some regular distribution updates, but none of them appeared to be X related at all. After hanging for a while, both programs exit with an error message:

optirun: [ERROR]Cannot access secondary GPU - error: X unresponsive after 10 seconds - aborting

primus: fatal: Bumblebee daemon reported: error: X unresponsive after 10 seconds - aborting

However, the secondary X server with nvidia driver actually does start up, and when I run, e.g.

DISPLAY=:8 xterm

the xterm window shows up on the external monitor connected to the Nvidia card, so it appears to be a communication problem within bumblebee. Running bumblebeed and optirun with --debug doesn't produce any useful information, both programs just hang for about a minute and then exit.

Any ideas how to fix this?

Answer 1

As usual, I've found the solution myself ~ 5 minutes after posting the question: I had edited my firewall settings, and they were too restrictive - in particular, they prevented bumblebeed from connecting to the X server via port 8001. Firewall settings adjusted, everything back to normal :-/

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(Edited the follow up comments back into answer _-Editor )

I used netstat -altup and saw that bumblebeed was in SYN_SENT state, which usually means that the initial connection was silently dropped by the firewall.