Wifi – Failure to obtain IP with ARP over Wi-Fi with personal Wi-Fi router in client mode

Your chosen solution works, but there are alternatives that don't involve arptables. (Christopher Cashell was on the right track, originally, but he was off by a smidge.)

In short, you want to set these parameters:

net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.all.arp_announce=2

These should be available when running a modern, 2.6 series Linux kernel. Check and make sure you that '/proc/sys/net/ipv4/conf//arp_announce' and /proc/sys/net/ipv4/conf//arp_ignore' exist on your system.

The 'arp_filter' parameter only works when your various IP addresses share a LAN segment but use different IP subnet. If they share the IP subnet, too, you need to use 'arp_ignore' and 'arp_announce', as above.

(I believe you may also need to set 'arp_filter' back to '0', too.)

What you want is actually possible, but requires a pretty recent Linux kernel (>= 2.6.34, or a backport).

The option you need is /proc/sys/net/ipv4/conf/*/proxy_arp_pvlan:

proxy_arp_pvlan - BOOLEAN
    Private VLAN proxy arp.
    Basically allow proxy arp replies back to the same interface
    (from which the ARP request/solicitation was received).

    This is done to support (ethernet) switch features, like RFC
    3069, where the individual ports are NOT allowed to
    communicate with each other, but they are allowed to talk to
    the upstream router.  As described in RFC 3069, it is possible
    to allow these hosts to communicate through the upstream
    router by proxy_arp'ing. Don't need to be used together with
    proxy_arp.

    This technology is known by different names:
      In RFC 3069 it is called VLAN Aggregation.
      Cisco and Allied Telesyn call it Private VLAN.
      Hewlett-Packard call it Source-Port filtering or port-isolation.
      Ericsson call it MAC-Forced Forwarding (RFC Draft).

The upstream commit adding this support is 65324144b50bc7022cc9b6ca8f4a536a957019e3.