Thanks for your feedback. I just disabled QoS entirely, the log shows:
Code:
Jun 09 23:37:04 dMP17 rc_service: httpd 1401:notify_rc restart_qos;restart_firewall
Jun 09 23:37:05 dMP17 syslog: Error locking /var/lock/qos_ipt.lock: 0 Already locked
Jun 09 23:37:05 dMP17 syslog: Error unlocking -1: 9 Bad file descriptor
Manually removed /var/lock/qos_ipt.lock, which was to my surprise created nearly 1,5 hours before I even made any changes to the QoS-settings, mentioned in
this post. Will turn back QoS back on now, with it's original settings (Adaptive mode, bandwidth auto) and see what happens. If that doesn't fix it, I'll reboot tomorrow and see if that fixes it.