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Getting Double NAT with my Netgear C6300 in bridge mode
Decided to get dedicated devices for my home network to allow more control and make my Netgear c6300 cable modem/router combo into just a modem. Put the Netgear in bridge mode which is turning off router mode which disables the NAT per the manual. Hooked up my new dedicated router and was getting a public IP for the WAN port (Perfect bridge mode looks to be working). Did connection tests on my game consoles and was showing double NAT. Ran a traceroute and am seeing my router as the first hop which is to be expected but what is this unknown private IP that is the second hop?
Tracing route to dns.google [8.8.8.8]
over a maximum of 30 hops:
1 <1 ms <1 ms <1 ms 192.168.10.1
2 11 ms 11 ms 12 ms 100.93.64.3
3 11 ms 10 ms 10 ms po-303-316-rur202.c2sdigital.ga.atlanta.comcast.net [68.85.91.29]
4 9 ms 10 ms 10 ms po-2-rur201.c2sdigital.ga.atlanta.comcast.net [162.151.88.233]
5 11 ms 9 ms 9 ms po-200-xar01.c2sdigital.ga.atlanta.comcast.net [96.108.116.97]
6 10 ms 12 ms 12 ms be-305-ar-in05.b0atlanta.ga.atlanta.comcast.net [96.108.0.45]
7 12 ms 14 ms 13 ms be-1305-ar-sp03.b0atlanta.ga.atlanta.comcast.net [96.108.116.249]
8 12 ms 12 ms 13 ms be-33031-cs03.56marietta.ga.ibone.comcast.net [96.110.43.73]
9 13 ms 15 ms 14 ms be-2311-pe11.56marietta.ga.ibone.comcast.net [96.110.32.30]
10 * * * Request timed out.
11 13 ms 12 ms 13 ms 74.125.245.89
12 13 ms 10 ms 12 ms 142.251.70.149
13 12 ms 11 ms 10 ms dns.google [8.8.8.8]
Trace complete.
I have factory reset the Netgear and put it in bridge mode again just for good measure. Hooked up my laptop directly to the Netgear and was getting a public IP. Ran traceroute again and this unknown private IP is the first hop? Is this a rogue router someone has hooked up down the street or does it belong Xfinity's end? How can I get rid of this double NAT and just have my one router performing NAT?
Accepted Solution
BruceW
Gold Problem Solver
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26.3K Messages
2 months ago
Addresses in the range 100.64.0.0 - 100.127.255.255 are "carrier grade NAT" addresses ("CGNAT", https://en.wikipedia.org/wiki/Carrier-grade_NAT). I fear that Comcast/Xfinity is not likely to change this for you, as most of their employees don't even seem to know what that is, or why the company uses it. Some have flat-out denied using it, despite traceroutes such as the one you posted showing CGNAT addresses.
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