No buffer space available
On occasion traffic on a NIC may have trouble getting out with an error similar to:
ping: sendto: No buffer space available
dpinger WANGW x.x.x.x: sendto error: 55
The most common causes of this are:
- No route to the target network (or no default route)
- Missing link route for a local target
- Stale state in pf sending the connection out an invalid path (reset states)
- Network memory buffer exhaustion - See Tuning and Troubleshooting Network Cards
- Faulty NIC and/or driver issue
- Sometimes resetting the NIC can bring it back again:
# ifconfig em3 down; ifconfig em3 up
- Faulty cable
- Traffic shaping (ALTQ or Limiters) dropping the packet
- Virtual NIC being throttled by the hypervisor or host, such as an AWS instance using more throughput than an instance size can support
- In this case, change the throttling in the host (not guest) or upgrade to a larger instance/higher tier on a hosted platform such as AWS.
- Virtual NIC being disconnected/disabled in certain hypervisors
- An otherwise overloaded NIC exhausting its send/recv buffers
- Other various switch/buffer/connectivity issues
Trying to bounce the NIC with ifconfig is the easiest thing to try first. After that, save/apply the interface settings on each interface (or at least WANs and the LAN in question). Check/(re)set the default route if it has been lost. Reset States. Replacing the cable may also help. Removing traffic shaping if it is enabled is also a good test.
Otherwise investigate the traffic on the NIC and look for other buffer-related causes. Seek help from pfSense Commercial Support for assistance in diagnosing the issue, or post on the forum/mailing list.