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Shaw (an ISP) recently decided to switch from supplying a basic modem, to supplying a combination modem/router, the Hitrom CGNM-2250.

The problem is, the router aspect of it is terrible. The admin UI is awful, and the signal quality is a joke. It was fine for a while, but now my sister has moved back in and it doesn't even reach her room.

I dug out an old Linksys that we used before, plugged it into an ethernet slot on the modem/router, configured it with WPA2, and got it working. The signal quality is almost twice as good.

I've never done this before though, and have concerns that complicating the setup like this may possibly introduce security concerns.

If I entirely disable the router aspect of the modem (by disabling the access points), should the combo modem behave just as a modem? Does chaining a router to a (disabled) router introduce any security problems?

bertieb
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Carcigenicate
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1 Answers1

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Will using a 'second' router cause problems?

Setting things up as you've described won't necessarily cause problems, inherently. There are a couple of considerations, however.

Use 'modem'/'bridge'/'passthrough' mode, instead of just disabling wifi

You say you have disabled the router aspect of the combo router/modem by disabling wifi. However, depending on how it is set up, it may still be acting as a router (negotiating with upstream etc) but on the wired interfaces.

You might run into 'double NAT'

Related to the previous point, if the devices are connected to the Linksys, they may be behind two levels of private networking- so-called 'double NAT'.

See How bad is double NAT, really? for more information. Depending on what you and your sister use your internet connection for, it might not be a problem; or it might be a massive inconvenience.

If you can set the device such that it acts simply as a modem, these issues can be avoided. Many combo devices can do this.

Does chaining cause any security problems?

Answering this is dependent on the specific configuration and devices involved, but it's worth bearing at least one security consideration in mind: upgrading router firmware. Routers can be targeted by exploits, and so they are worth keeping up-to-date (as well as the devices behind them).

As you have two devices, it is worth keeping both of them as up-to-date as possible to reduce the surface area for attack.

bertieb
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