Friday 22 September 2017

WiFi Coverage - Stage 1

The WiFi coverage through the house has never been particularly great, probably due to all the internal walls being brick, rather than wood and plasterboard. The broadband router and WiFi access point is in the hallway, near the telephone socket, probably just like a lot of homes. Unfortunately this puts it in between two brick walls that neatly divide the house in half, one of which also incorporates the chimney. The signal strength in the hall is superb, but by the time you get a room away it has dropped off noticeably, and it has completely gone by the patio. When we moved in a few years ago this wasn't a huge issue, but the number of wirelessly connected devices has slowly increased, as have my expectations. Additionally I'm spending more time in my man cave in the workshop, 30 metres or so up the hill from the house. Initially I used some powerline adaptors to serve up internet access from the router in the hallway to the workshop. But the combination of additional RCBs, 30 metres of cable and a second consumer unit meant that the powerline adaptors struggled to both maintain a connection and provide sufficient bandwidth. So a temporary fix was to run a very long network cable through the garden alongside the satellite tv cable, until I get around to digging that trench I was talking about several years ago.

The over-winter fix is the addition of a point to point wireless link, using a couple of WiFi access points, one in the house and one in the workshop. As well as providing internet to the workshop, they should also function as standard access points, eliminating the coverage blackspots in the house and garden. As we have a DrayTek Vigor 2860 router, I ordered a pair of DrayTek VigorAP 910C ceiling/wall mount access points, which would allow me to manage all three items from a single dashboard, and not have to log into each one individually to make any changes. I've been pretty happy with the 2860 router which, whilst being pretty expensive and not having the most intuitive user interface, has been very reliable, gets regular firmware updates from DrayTek, has got the most out of our broadband, and has a wealth of functionality. For example, when (if?!) fibre broadband arrives in our corner of Ironbridge the support for it is already built in.


When the VigorAP 910C access points arrived, the first thing I did was read the MAC addresses off of the labels, and add them to the routers IP binding table, so I'd know which IP address they were using if I ever needed to configure them individually. Then once the access points were plugged in, I opened up the router's management web page and opened up the Central Management section. The two 910Cs were automatically recognised and listed in the status table. The next thing to do is give the access points friendly names, so that you don't have to remember which access point is using which IP address.


The status table also stated that both access points were sent to me with v1.2.0 firmware, the last critical firmware update, but the DrayTek support website was showing a v1.2.1 regular update with a couple of new features and improvements, so I updated both access points as a matter of course. Using the 2860 router's central management feature, you can update multiple access points in one go.


You can also set up a WLAN Profile, which is essentially a template configuration for an access point, which you can then push to all the access points in one go. By doing this I ensured that finger trouble didn't mean that I ended up with different configurations at either end of my wireless link, and things like SSIDs and pre-shared keys were the same everywhere.


Anything you can configure on the access point itself, you can set up in the profile. It would be nice if you could duplicate the wireless settings from the router itself to the access points, but as far as I can see you have to copy the settings over to a template manually.

The long term plan, once that dastardly trench is dug, is to use the two 910Cs purely as access points, and have a wired link between house and workshop. So seeing as the temporary cable was in place, I first set up the access points in AP mode. This also was good to demonstrate the directional antennae in the access points, unlike the router which has omni-directional antennae. The 910C are designed to be wall or ceiling mounted, and so focus the majority of their wireless energy to the front of them. With the workshop being up the hill from the house, I mounted the access point there on the ceiling, with a line-of-sight to the house. At the house I went into the loft and mounted the access point on the side of the chimney, not only facing the workshop but also the patio and garden. There's going to be some energy wasted up into the sky, but the coverage in the house has been transformed, and you now have to go into the lee of the chimney to see any drop off in signal strength.

The next step is that point-to-point link, so that the network cable can be removed from the equation. The VigorAP 910C has several operating modes, one of which is AP Bridge - Point to Point mode.


This mode is only available using the 2.4GHz band, not the 5GHz band, and in this mode the access point doesn't broadcast an SSID so that other wireless clients can connect to it, it simply connects to another 910C access point. There are four key configuration changes to make for this mode. 1) Both ends of the link must be set to AP Bridge Point to Point mode. 2) Both ends of the link must have static IP addresses, and their own DHCP servers turned off. 3) Both ends of the link must be configured to use the exact same wireless mode, channel and channel width. 4) Each end of the link must be configured with the MAC address and security settings of the other end of the link.



Essentially in this mode, any network packet arriving at a 910C is duplicated at the other 910C, and in effect they become transparent to the network. This means that when devices, such as the IP cameras and my desktop PC, boot up at the workshop they can still request IP addresses and other network configuration information from the DHCP server in the router, because every packet transmitted in the workshop is replicated in the house. Just like having a cable, which we now don't.

For the 910C in the house, I've also left the 5GHz band in regular access point mode. So wireless devices in and around the house will connect to either the router or the access point depending on which signal is stronger. At the workshop the 910C cannot internally connect the point-to-point link with the 5GHz access point, so whilst I can turn on the 5GHz access point mode at the workshop, anything that connects can only see the other devices at the workshop, nor the house or router.

When I get the time, I'm going to investigate AP Bridge - WDS (WiFi Distribution System) mode, which apparently enables the 910Cs to be access points in both the 2.4GHz and 5GHz bands, and simultaneously keep the 2.4GHz point-to-point link in place. That would allow me to connect wireless devices, as well as wired devices, to the 910C at the workshop.