[ale] Weird arp problem (repost)

[James Sumners]

Reposting this because I don't think it came through last time. I believe
the list was broken...

I have an htpc that _seems_ to be dropping off of my network at least once
per week. It is connected via 802.11n to my Ubiquiti AC-PRO => Ubiquiti
8port managed switch => 24port Netgear dumb switch => pfSense router. When
the system disappears I can:

1. Ping my router and google.com from the system
2. Ping the system from my router

I cannot:

1. Ping the system from any of my other computers, even on the same vlan
2. Traceroute to the system from any of my other computers

This is what I see in my arp cache during the problem:

```
htpc.example.com (192.168.2.9) at (incomplete) on en1 ifscope [ethernet]
```

>From this system with the invalid arp cache I can do the following and
re-establish the connection:

```
arp -s htpc.example.com <htpc's MAC address>
```

What could be causing all of my other systems, _except_ my router, to lose
the arp path to this system? If I reboot the htpc then all of the other
systems are able to find it again without having to manually re-specify the
path.

-- 
James Sumners
http://james.sumners.info/ (technical profile)
http://jrfom.com/ (personal site)
http://haplo.bandcamp.com/ (music)
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