On Sat, May 18, 2019 at 07:52:39AM -0700, d...@lutean.com wrote:
> I have seen a few devices that consistently ignore DHCPOFFER messages. After
> some tinkering with standards compliant permutations of offers that they
> might not handle properly (e.g. lease times and RFC6842 client-id options),
> I got frustrated enough to try some standards non-compliant possibilities.
> It seems that despite requesting a broadcast response, they actually only
> receive and/or accept the DHCP message if it is unicast.
> I tested this by creating a "-dhcp-unicast" configuration option that is
> identical to the "-dhcp-broadcast" option but with the exact opposite
> meaning, namely regardless of what the client asks for, use L2 unicast
> responses. With that change the devices (some Honewell thermostats and Sony
> TVs) started working.
> Has anyone else seen problems like this?

Yes, however not at first hand.
It has been reported to this mailinglist.
I have no details at hand, a search on the archive should yield it.

> When I search on Honeywell Lyric thermostat Wifi connection issues,
> it does seem like a lot of people have undiagnosed problems with them,
> so this may be the cause.
> Has anyone else seen devices that don't seem to respond to DHCPOFFER
> messages? If so, do the corresponding DHCPDISCOVER messages have the
> broadcast bit set?

Geert Stappers
Leven en laten leven

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