I have little understanding of Wi-Fi and the correct terminology, so please bear with me here...

I have a Wi-Fi re-transmitter at the front of the house, connected to my router by Ethernet cable. It works fine, providing coverage to pretty much the whole house.

Operative words here are "pretty much". My wife likes to hang out on the deck on the back side of the house, and coverage there is pretty spotty for her iPhone and iPad.

I have no more ports available on the router, so I can't just duplicate what was done at the front of the house.

Can you recommend a simple and inexpensive way to get wireless coverage on the rear deck? It is only about 30 feet away from the router (Linksys WRT-54G) but the signal does have to go through a brick wall to get there.

What should I do?

tanstaafl.

As I recall, the building is more or less L-shaped, isn't it? So, perhaps a Wifi Access Point over in the opposite wing (brother's?) might provide coverage across much of the rear garden and deck.

??

As for "no more ports available", that is "fixable" by simply plugging an ethernet switch into one of the four ports, and then plugging other stuff into the switch. The switch itself (depending upon model) could provide anywhere from four to 48 new available ports for stuff.

A simple 5-port ethernet switch should cost under US$20.

Depending on your current devices, upgrading to a better Wi-Fi access point would probably be a better solution in my opinion.

A WRT54G is"only" 802.11g

An 802.11n access point should theoretically double your range if you have all 802.11n or better devices.

802.11g is very old so I'd guess it's unlikely you have anything that's 802.11 b/g only. Certainly any tablet/cell phone should be 802.11n or better. e.g. iPhone 4 onwards (which was released in 2010).

OR

Otherwise a simple Wifi retransmitter like you already seem to have should be doable with WDS (which is basically the repeater), but note that halves your bandwith.

You mention your re-transmitter plugging into the router. In that case it's probably an access point in its own right rather then a repeater/retransmitter. Do you have two separate access points setup in your phones/devices?

So if I understand this correctly, my simplest solution would be to buy a switch to gain more router ports, then run an Ethernet cable from the switch to a Wi-Fi access Point device out on the back deck.

There is no point in my asking for recommendations of what switch and what access point device to buy, because I will be limited to whatever my local computer supply store has on the shelves. High performance (bandwidth and speed) are not a priority here, the nearly exclusive use will be for my wife to look at cat pictures on Facebook.

Do I kind of have the idea? (I told you I know next to nothing about networking and Wi-Fi, it's all black magic to me.)

tanstaafl.

I think that's generally the best idea.

You might put the access point on a window sill just inside from the deck to keep it protected from your nighttime weather, though. If it's just glass it shouldn't attenuate the signal as much as concrete (iirc) walls.

If you're using a couple router type devices, you'll need to do something extra to allow all devices to see each other (network printing, for example) in your house.

-jk

Yup, that's the idea. Pretty much ANY 100mbit or gigabit ethernet switch will do the job, so just get the cheapest one. Avoid "hubs" (different from switches, even though they look alike).

I don't know if it's applicable here or not, but sometimes running an ethernet cable is impractical or hazardous (eg. across an open floor or hallway). For such situations, "powerline" adapters are very handy.

The idea is they begin as a basic pair of devices. One device is plugged directly to a wall receptacle near your router, and a short ethernet cable is used to connect it to the router or switch. The matching device can then, generally, be placed anywhere in the residence, again by plugging directly into a wall receptacle near the desired location. The house's AC power wiring acts as a "network cable" between the two devices.

That second device can then provide a local ethernet jack to run a short cable to a computer or wireless access point, or it could itself be a wireless access point. Eg:

https://www.amazon.ca/TP-Link-ADVANCED-Universal-Powerline-TL-WPA4220/dp/B00HSQAIQU/

The more basic models (without the built-in Wifi in the second device) are trivial to install: just plug them in, and press a button on each of them within a minute or two of each other, and they will self-detect and configure.

EDIT: Once one has a matched pair of such items working, you could purchase additional ones from the same model line (same manufacturer) to add more remote ethernet jacks, one by one (no need to use pairs after the first two).