I "upgraded" to a SB6183 about 2 weeks ago..
The modem replaced a DPC3010.
The modem is directly connected to a 1u E31230 with linux that handles NAT/firewall.
The wifi AP is in bridge mode and connected to the lan via a gigabit switch
Immediately after "upgrading" I started noticing connection reset errors, poor throughput from my wired desktop machines and complete failure on wireless devices.
After much digging I discovered that the connections were being reset because of incorrect tcp window sizes being sent in the SYN and SYN/ACK packet headers.
I was able to alleviate the problem by disabling tcp_timestamp on the machines I could control it on. I was unable to resolve the problem on the other various devices like Roku, iOS, etc, that do not allow you to make such changes.
I found what I think is a related blog at : http://blog.dan.drown.org/sb6183-dropping-ipv6-traffic/ and a thread on DSLReports covering this problem: http://www.dslreports.com/forum/r29569626-IPv6-SB6183-IPv6-problems
I removed the 6183 and replaced it with the DPC3010, making no other changes to my network. The problem went away.
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