SOLVED: Failed to send ARP table population packet

Configuration
1 
Home Assistant 0.96.5
arch	armv7l
dev	false
docker	false
hassio	false
os_name	Linux 10 (Debian Buster)
python_version	3.7.3
version	0.96.5
virtualenv	true

How can I prevent these many entries in the log file.

2019-08-05 03:42:09 ERROR (SyncWorker_14) [getmac] Failed to send ARP table population packet
2019-08-05 03:42:14 ERROR (SyncWorker_14) [getmac] Failed to send ARP table population packet
2019-08-05 03:44:10 ERROR (SyncWorker_19) [getmac] Failed to send ARP table population packet
2019-08-05 03:44:15 ERROR (SyncWorker_19) [getmac] Failed to send ARP table population packet
2019-08-05 03:46:11 ERROR (SyncWorker_8) [getmac] Failed to send ARP table population packet
2019-08-05 03:46:15 ERROR (SyncWorker_8) [getmac] Failed to send ARP table population packet
2019-08-05 03:48:12 ERROR (SyncWorker_7) [getmac] Failed to send ARP table population packet
2019-08-05 03:48:17 ERROR (SyncWorker_7) [getmac] Failed to send ARP table population packet
2019-08-05 03:50:13 ERROR (SyncWorker_5) [getmac] Failed to send ARP table population packet
.... and many...

It is probably because the “arp” unreachable devices as:

arp -an | grep 10
? (10.1.1.227) at <incomplete> on eth0
? (10.1.1.165) at <incomplete> on eth0
? (10.1.1.214) at <incomplete> on eth0
? (10.1.1.251) at <incomplete> on eth0
? (10.1.1.152) at fc:a1:83:15:55:77 [ether] on eth0
? (10.1.1.98) at e0:f8:47:1b:b5:02 [ether] on eth0
2

The problem was the device_tracker settings:

scan_options: -Pn --host-timeout 5s

New setting works now, w/o any errors

device_tracker:
  - platform: nmap_tracker
    interval_seconds: 120
    consider_home: 180
    track_new_devices: true
    scan_options: -sP --host-timeout 5s
3

Just saying thanks.
Helped me also
Also you need to open port 55555 on your firewall, because the getmac script is trying to send a packet on that port…
(Only in the LAN direction)

cheers
tom