[SOLVED] 2 ISPs - 2 ADSL Modem/Routers - Do I need a Multi-WAN Router?

[roby24]

I've been reading for a while about the topic, but I still can't wrap my head around it, so before investing in new hardware I'd like to get some opinions.

Scenario

• I have 2 ISPs
• I have two DSL modem/routers provided by the ISPs (ZTE ZXHN H267A & TP-Link TD-W9980)
• Both modems have WAN/Ethernet ports.
• 1 Single DSL cable connected to one of the routers.
• 1 PC connected to the router through ethernet cable (I also have a Wireless card that I generally don't use).

Goal

I'd like to freely switch between connections in case one fails. Just to be clear, It's not a requirement for me to configure a failsafe (E.g: automatically switch to the other connection). Basically, I'm comfortable physically switching between routers and changing configurations if that's what it takes, since the connection doesn't get interrupted often (But when it does, it can be hours until they fix it).

Question

All the scenarios I came across while reading already take into account either a third router, a multi-WAN router or a switch. I'd like to understand what's the minimum equipment I need to achieve my goal. Is a multi-WAN router mandatory? If not, do I need additional equipment or can I switch between routers if I use a certain configuration on one of them?

Both routers are configured as DHCP right now. I've read on multiple threads that for this setup to work, one need to be static (If they are connected to the same network). Right now, if I connect my PC to one router, everything works as intended. But if I switch to the second one (DSL & Ethernet Cable with default configuration from the technicians) it doesn't work. Not required, but I'd also like to understand why this doesn't work like that if you know the reason.

 

[SamirD]

So in the simplest scenario, you simply disconnect the ethernet from the isp that is not working and connect the one that is.

As far as why switching does not work--the only answer I have to that is that you are doing it too fast or are not also resetting the ip configuration on the pc when you do. Personally, if this is just for one pc, I would set up a static IP on the 'backup' connection and a different gateway on the same subnet (like 192.168.1.50) and just change the ip configuration on my computer when having issues.

Mult-wan routers are cheap these days and much more reliable than they were back when I did my first multi-wan connection back in 2004. I would simply get one and then you don't even have to think of these issues and won't even noticed when one goes down. It's bliss.

 

[roby24]

Thanks @SamirD, that answers my question. I wanted to confirm if the Multi-WAN router was mandatory for this setup, but it seems I must be doing something wrong. Anyway, I can figure that out with some testing.

I might still take you up on the advice and buy the router. Just wanted to avoid the scenario of buying it and then discovering that it's not what I need 🤣

 

[roby24]

Ok, while looking for the Multi-WAN router, I actually came across what I think it's the main problem when I was asking myself "What the hell do I do with the DSL cable?"

Since both connections are DSL (And I only have one line), the last ISP I've installed configured the line to use their equipment (whatever that entails).

Unfortunately, I can't install cable here, so I'm stuck with two ADLS. In that case, it seems what I want to do is not possible even with a MultiWAN router unless I install a second line? Or something of the sort?

I'll leave it in the back burner for now, but if anyone wants to add/confirm/deny this appreciate it.

 

[bill001g]

My guess is you can run both on the same cable....well likely with dual phone adapter.

So most DSL only uses 2 wires....some users 4 but that is a form of VDSL. Most phone cable has 4 wires so it can run 2 DSL connections but you need to split the wires. What is common is the center 2 wires carry 1 signals and the 2 wires outside these center 2 carry the other. Unlike ethernet you could just strip back the main insulation and crimp on 2 jacks. They also make adapter that convert this to 2 single wire jacks.

So now maybe you have 2 dsl routers that function.

What you do to make it easier to switch between them is first leave 1 router as default....let say it uses 192.168.1.1. On the other router assign it 192.168.1.2, turn off the DHCP server and plug the 2 routers together with a ethernet cable. You will also have to block the 192.168.1.2 ip from the first router DHCP pool

Now your pc will use 192.168.1.1 by default. If want to switch delete the 0.0.0.0 route and add new 0.0.0.0 route and point it to 192.168.1.2. If you get very ambitious you can actually run both routers by carefully sending only certain IP addresses to the 192.168.1.2 rather than the 0.0.0.0 (default route). This is all done with the ROUTE command on the pc.

 

[SamirD]

Thanks @SamirD, that answers my question. I wanted to confirm if the Multi-WAN router was mandatory for this setup, but it seems I must be doing something wrong. Anyway, I can figure that out with some testing.

I might still take you up on the advice and buy the router. Just wanted to avoid the scenario of buying it and then discovering that it's not what I need 🤣

You're welcome. Yeah, you have to know what you are doing because it's not the usual network since you have multiple gateways. But you can set up such a network without a special router if you know what you're doing, even though such a setup isn't utilizing your accounts in the best way.

Depending on how fast your dsl accounts are, you might be able to pick up an older multi-wan router, the Cisco rv016. This beauty was able to use up to 7 wan connections at once and I was using it with 3 on my first multi-wan setup. But it is limited to 40Mb/s wan to lan so if you've got faster connections and want to utilize all the bandwidth, it wouldn't be the best. But if you only want the ability to switch and have automatic failover, it might be right up your alley.

 

[SamirD]

Ok, while looking for the Multi-WAN router, I actually came across what I think it's the main problem when I was asking myself "What the hell do I do with the DSL cable?"

Since both connections are DSL (And I only have one line), the last ISP I've installed configured the line to use their equipment (whatever that entails).

Unfortunately, I can't install cable here, so I'm stuck with two ADLS. In that case, it seems what I want to do is not possible even with a MultiWAN router unless I install a second line? Or something of the sort?

I'll leave it in the back burner for now, but if anyone wants to add/confirm/deny this appreciate it.

You can still run a multi-wan no problem. I don't know of any multi-wan router that has built-in dsl modems, so you will need to use the existing isp equipment anyways. You simply connect each of the lan sides to the mutl-wan router and make sure both dsl routers are on different subnets.

 

[roby24]

Great, thank you both @SamirD, @bill001g.

@bill001g, I didn't know I could do that. Seems I will need to tinker a bit, but if I can do it it's worth a try. I'll update as soon as I get a working solution.

 

[SamirD]

Yep, bill001g's solution isn't easy to figure out, but one you do, it's cake since you can set up a batch file to do the routing table entries.