A quasi-review of the ASUS AC1900 RT-AC68U router and Bell's ZTE MF275R Turbo Hub (LTE). Other carriers also offer this same device.
As I mentioned in a previous post, getting satisfactory Internet access in the Canadian country-side can be a challenge especially if you have specific needs and don't want to spend a huge fortune (just a small fortune, perhaps). [People living in medium to large-sized towns or cities in Canada generally have access to faster, cheaper, Internet.]
On the one hand there's DSL which is relatively cheap, plans are readily available with no caps, static IPs are available, but the speeds are slow. On the other hand LTE is (in my specific case) >8x faster, but comes with caps, doesn't allow static IPs, and is more expensive.
How to decide between the two? Get both!
Having decided to get both, the next job is to decide how to manage your devices. A simple solution is to run two access points and make each of your devices log into one access point or the other. The ZTE is both an LTE modem and a dual-band WiFi access point all rolled into one device. A regular DSL setup would involve the phone line going to a DSL modem, then out from the modem to a router (which serves as an access point). But if you want the possibility of sharing both Internet connections between all your devices dynamically, a dual-WAN approach is better.
The devices you have in your home which connect to your router via WiFi are described as being on the LAN side of your router. The pathways which lead from your router to the Internet are described as being on the WAN
side of your router. In the vast majority of cases there are usually
many LAN devices and only one WAN connection. In my case I have two ways
to get from my router to the Internet; this is described as a dual-WAN
setup. Most routers expect the "usual" setup and therefore only provide
one WAN connection. In order to run a dual-WAN configuration you have
to own a router that specifically supports this topology. I own an ASUS
AC1900 RT-AC68U router which is one of the few that support dual-WAN and is the one with which I am most familiar.
Other routers support dual-WAN too, you'll need to check the specs of
other routers to verify whether or not they have this feature.
Let's say you do several Internet things with one device: you perform some large downloads from specific sites, and you also want to play some online games. For the downloads you'll want to use the DSL (which, although slower, will not incur large data costs since there's no cap). For gaming you'll want to use LTE. If both Internet connections are on separate routers, you'll need to switch which access point your device uses when performing each of these tasks. Plus you won't be able to perform both tasks at the same time; you'll need to do one task while connected to one access point, then switch to the other access point in order to perform the other task.
Another consideration is reliability. Although both technologies have pretty good uptimes, there will be times when one or the other might be down (especially DSL, I'm not saying DSL goes down every week or even every month, but it does go down and when it does it's very annoying). When one of your Internet connections goes down, you'll need to switch your devices so that they are all on the working access point. Not all devices are smart enough to switch automatically. The flip side of the same argument is: if you use a dual-WAN setup, you only ever have to program one access point (SSID) and password into all your devices and they'll all be able to access the Internet through either Internet connection (WAN interface) regardless of which service is up or down.
In my specific case, I'm using the ZTE MF275R Turbo Hub which I obtained through Bell Canada. If you read through this device's specs you'll find that it only allows 20 devices to be connected to it at a time. This doesn't sound too bad, but the device actually only allows up to 10 devices to be connected at any one time to each band. Since the device supports both 2.4GHz and 5GHz bands, it smudges the truth a little and claims up to 20 devices. So if you have more than 10 older WiFi devices, they can't all connect at the same time (since they'll all be using the 2.4GHz band and probably don't have support for the 5GHz band). My point being, another good reason to consider plugging your Turbo Hub into your router is that most routers don't have this artificial limitation, so you could connect more than 10 devices on any one band and route them all through your LTE Internet connection.
In other words, there are a number of good reasons to connect both Internet sources through the same router to feed your set of devices.
When the AC68U was introduced it did not support dual-WAN. But since its introduction, ASUS has been producing firmware updates and somewhere along the way it added dual-WAN functionality to this device. The last time I checked, however, the "latest" manual still did not reference this new functionality, so even if you download and read through their manual you might not believe this device supports this feature. There is a chance, however, that you might buy a "new" AC68U router to find it is loaded with old firmware. Therefore you can't do dual-WAN "out of the box". In this case you'll need to update the firmware yourself. In any case it's nice to see a manufacturer's stock firmware actually adding to the value of a device over time (instead of a rising trend among manufacturers to use firmware updates to take away features from the consumer!).
As part of its dual-WAN configuration, the AC68U allows the user to define a set of rules (up to 32) whereby it can be specified which LAN device should use which of the WAN interfaces when connecting to which machines on the Internet. It's a great addition, but not perfect. The rules can only be defined in terms of source and destination numerical IP addresses. First of all, it means you have to configure the AC68U's DHCP server to give static IPs to your devices (not a big deal). Secondly, it only works if the machines to which you are connecting (on the Internet) have static IPs themselves (this is getting harder). Alternatively you can leave the destination IP blank, in which case the AC68U will fill in the destination with "all" when you add the rule. In this way you can specify that a given device (say, a Roku) will always only use one specific WAN interface (e.g. the DSL) for all Internet traffic. For my purposes, I can live with these restructions, but I could certainly see how some rules would be better described by source or destination port number/protocol, or DNS name.