My provider has deprecated our modem and TV. How can I save my existing household network?

Question

I had a Rogers' cable modem as my internet and old-school coax TV. Rogers has deprecated those systems as of two days ago. I have a few more days before I can't send the new Bell gear back (next Monday) so I need to get the networking sorted out asap.

Before this, I had the Rogers' modem set to bridge mode and my ASUS RT3100AC Wap/Router with the only DHCP server and my network behind that. It served 2.4 and 5.0 networks. No fuss.

The new provider (Bell, but Rogers is the same) uses a modem (Gigahub Fast 5689E) fed by a optical cable and each of our 4 TVs need a TV box (Arris 7802). There is no visible bridge mode.

Because the TV boxes probably need to be on the Gigahub (via the wireless, unless I need to get long, long ethernet runs) and I want my Asus RT3100AC WAP router and the network behind it to still work, I need to figure out what could work.

Router in front of Bell modem drops out TV This above answer for a tangential scenario reveals that Bell uses VLANs (35 and 36) - one for TV and one for internet. However, you can't see that in their Gigabit's exposed entries. And it just handles that. But if I put the TV boxes behind my ASUS box, I suspect it'll be a problem just as the fellow in the question had. So TV boxes need to be on the Gigahub.

The Gigahub will need to run DHCP for the TV boxes. Everything else will need to continue pulling DHCP leases from the ASUS box.

But can this work? And if not, what might?

My thought: 1). The Gigahub DHCP dispenses 192.168.11.x with ranges 220 to 240 (for the benefit of the LAN ports and the 4 TV boxes. 2. The ASUS DHCP dispenses 192.168.11.x with ranges 20-70 (for the benefit of all the stuff in our internal household network). 3. I plug an Ethernet cable (Cat 7) into fast ethernet (10 Gbps) port on the Gigahub and run it to one of the LAN ports on the ASUS.

To me, they are both dispensing 182.168.11.x range addresses but without overlap and thus my brain thinks perhaps this could work?

I'm not 100% happy to set my Asus RT3100AC into the Gigahub's Advanced DMZ mode, though I guess that might not be different than the old Rogers modem being in bridge mode - no protection in either case.

Double NAT has some sort of note from the company or the FCC about that feature being problematic on the Gigahub so I think that's out.

What's my best setup? Can my idea above work (two DHCP servers serving the same network with differing ranges)?

I'm thinking a problem is going Gigahub LAN to ASUS LAN and thus am avoiding the ASUS security that happens on the WAN port. When I try to put a cable from ASUS WAN to the 10 Gbps on the Gigahub, I get 'no internet'. ASUS has always run 'auto' for the protocol for the WAN. My options are limited to (auto, static IP, L2TP, P2TP, and PPPoE).

Answer 1

To me, they are both dispensing 182.168.11.x range addresses but without overlap and thus my brain thinks perhaps this could work?

Not really, because there is no boundary between them that would stop the DHCP offers from going across the other side of the network.

With a typical home router such as your ASUS, all LAN ports are connected together as if you had an Ethernet switch, and the Wi-Fi is likewise directly connected to the LAN port group. The only network boundary (i.e. the router proper) is between the WAN port and the group of the LAN ports, but there is none between the individual LAN ports (nor between them and Wi-Fi); it's all the same network.

Meaning, if your laptop sends out a DHCP discover request, the packet will go straight through the ASUS and will be received by the Gigafast, and the DHCP offer from the Gigafast will likewise go through in the other direction. The result is that your laptop will get DHCP offers from both devices and will pick one unpredictably. It will appear to kind of work, sometimes.

The reason I need a DHCP server on the ASUS box is for features I'm using in that box [...] MAC addresses restriction on both wireless networks plus parental features and time restrictions - all are tied to MAC address.

In that case, the "New Setup" with a LAN-to-LAN connection will not work for you, because (as mentioned before) there is no boundary between the LAN ports of the ASUS box – nothing that would prevent a Wi-Fi client of the ASUS from bypassing all restrictions, either by manually setting the gateway IP address on their PC or even through luck (having the PC pick up a lease from the Gigafast).

Practically, your options are:

• a) configure completely different LAN subnets on the two routers, connect the Gigafast to the WAN port of the ASUS, and figure out why the WAN port wasn't working for you earlier;

• b) disable DHCP service on the Gigafast, then manually configure the ASUS to use Gigafast as its own gateway (if it lets you do that – some home routers really insist that the gateway must be on the WAN port);

• c) disable DHCP service on the ASUS and use it only as a Wi-Fi access point without any of the "parental" features.

Answer 2

The solution that worked after a couple of stabs at it With help from @u1686_grawity was this:

1. Gigahub Fast 5786E has a unique network.
2. Asus RT-3100AC has a unique network.
3. Ethernet from the 10 Gbps port on the Gigahub to the ASUS RT-3100AC WAP Router.
4. Reserve the local address on the Gigahub being used by the Gigabhub port that will take data to the ASUS. That way if the ASUS has to be rebooted, it will get the same address. (may not be necessary, but I like it to be reserved so I don't have to go hunting for it if I want to access it)
5. Asus has WAN setting 'auto'.
6. Reboot both boxes (Gigahub and ASUS RT-3100AC).
7. TV Boxes use the frequency hopping wifi to connect to the Gigahub.

Now things work as they are supposed to.