Hitron 4582 in bridge mode: Alternative IP address?

[Johnster]

Hi,

I'm moving from an older Hitron modem to a 4582 with a new GB plan and in reading up on it I've come across an issue.  If I'm reading the docs correctly, once the modem is in bridge mode, it uses the IP address 192.168.100.1.  Is this configurable?  My entire home network is based on the 192.168.100 subnet with my router using 192.168.100.1.  I will not be able to have the same IP on two different interfaces on the router so unless I can configure the modem to use a different IP in bridge mode I'll have to re-do all of my internal leases and DNS entries.  Can I change the bridge mode IP address of the CODA4582U?

Thanks

[Datalink]

HI @Johnster, sorry but the IP addresses used by all Rogers modems to access the modems are not configurable.  They're set in stone, so to speak, so, customers have to work with the existing addresses.  

Just to note, with the CGN3xxx and CODA-4582 modems, customers can use two routers, connected to different modem ports when the modem is in Bridge mode.  The end result is that both routers will have their own independent IPV4 and IPV6 addresses and will operate networks that are independent of each other.  You can use any two of the four ethernet ports that the modems have.

[Johnster]

Hi,

Thanks for replying.  This isn't good news, I have ~100 DHCP reservations and LOTS of IoT devices that will not easily be re-addressed to a new subnet.  I guess alternatively I could set the router to .2 as the gateway address but that just goes against networking protocol (and I'm convinced something somewhere would break).  It's handy that I can connect another device and get a WAN IP, but I'm not sure it will do anything to address this issue.

Thanks

John

[Datalink]

Yup, that's the unfortunate side effect of changing modems.  Fwiw, the XB6 and XB7 modems which are used by the new Ignite Tv service use 10.0.0.1.  I believe that IP address is the same for Gateway and Bridge modes but don't quote me on that one.  

[WestPoint · Accepted solution]

If I may say, I don't think the 192.168.100.1 'modem' address will interfere with your network setup... from my experience and extreme research on the issue it shouldn't really.

This is because, and only because, your going to use bridgemode. If you left the CODA in Gateway mode, it might/would.

But when a Gateway device, considered a 3 layer device, is put into Bridgemode, this quite litterally disables/turns off, layer 3 of the device, the Router Layer, and leaves Layer 2, the Modem Layer running. Effectively, this completely disables all DHCP control/usage within the Gateway itself, meaning, there is NO Local LAN address you can access the configuration pages in the device itself from, the Gateways "ip address" effectively becomes your WAN IP address, and is indistinguishable from that address from within your LAN network.
(I have confirmed this 100's of times, the configuration access to the modem is lost immediately after turning to bridgemode)

This now makes your network safe-guarded from the issue your concerned about. As long as you do not try to use the WAN IP as your network base, and you continue to use 192.168.xx.xx in your LAN setup, than you should be absolutely fine from my experiences. I do avoid assigning possible main addresses, 192.168.0.1:10, 192.168.100.1 , ect to my +75 devices DHCP reservation list, but I doubt this is the only reason I have never had issues, even though I do use 192.168.0.xx LAN addresses not 192.168.100.xx addresses.

WORST CASE, put a DHCP reservation in your router, using your Modems MAC, and set to 192.168.100.1, and that way your devices don't try to take it and interfere with anything ..... you should be able to set your Router itself to use 192.168.100.2 instead, atleast I know my Asus Routers allow me to manually set my LAN Host Name, Domain Name, IP Address and Subnet Mask. Set that to 192.168.100.2, and add the DHCP reservation for your Modem to get 192.168.100.1, and that should resolve the issue, IF, and I stress, IF, it even happens, which I would be doubtful of, as I originally stated.

[andorejunior]

Im facing a similar concern and in my many open tabs looking for some information, your post has been the most helpful. Thanks for that. (Also quite recent!)

Long story short, I had a power outage that changed my IP addresses from 192.168.0.X to 10.0.0.X. I have some devices set to static IPs that I now cant reach. FYI I have a CODA 4582 in bridge mode with a Netgear R7200 router.

This is my current LAN setup post power outage https://imgur.com/LerQcKv

Im wondering if simply changing the IP addresses as shown in this link is all that would be needed https://imgur.com/9npOFpu

Thanks for any help that you can provide!

EDIT - Im also having my hard wired PC and two TV's speed periodically dropping to sub 10Mbps now, not always but it happens daily. WiFi is perfect at 500Mbps+ Not sure if thats somehow related but I thought Id mention. Thanks again. 

[Johnster]

In my case, the IP address conflict has had no effect on my network, so I've left it as-is.  I can say though that the modem has retained the 192.168.100.1 address, which I can access if I use an ethernet patch cable directly to a computer set to 192.168.100.X/24 and the modem.  Since this address is on the WAN port of my home router it doesn't seem to be causing any issues with my internal networking, but it is there nonetheless.

@andorejunior I find it odd that a power failure caused your router to start handing out addresses in a new range.  Do you know what the lease duration is? Assuming it's something reasonable like 8 hours,  you could just change the lease range back to the range you've posted in the screenshot and wait for all of the DHCP clients to renew with the new address.  This was essentially the strategy I was going to use if I had to redo the entire network range at home.  If you have some stubborn clients or want to force a new address, a power cycle will cause your clients to request a new IP.  

Hope this is helpful.

[andorejunior]

Thanks for your comments, it was helpful and Im back up up and running!