A little different scenario on my end, but it was a SPA 502G which was getting the DHCP failed reason, and would reboot about every 3.5 times the lease time. This fix took more then a year, but early on we noticed statically setting the phone was the fix but we could not do that for this customer. To fix I applied to the phone: <DHCP_Option_To_Use group=\"Provisioning/Configuration_Profile\">82,160,159,60,43,125</DHCP_Option_To_Use> <DNS_Server_Order group=\"System/Optional_Network_Configuration\">DHCP,Manual</DNS_Server_Order> Mainly DHCP option 82 being added was the fix from what I could tell. After I added it rebooted 5 more times (a lot more than 3.5 times the lease time) this time around but then stopped with no further problems after that.
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