Airport Express - WiFi vs Airplay

my question is whether an Airport Express used to feed Airplay via 3.5mm jack into the hifi is also functioning as a wifi extender at the same time

The answer is NO.. it is not working as a wifi extender if you are using another brand as your main wireless router.. ie it is not an Apple router.

If your main router is Apple OR you can introduce an apple router into the mix.. then YES, you can use the airport Express to extend the wireless network as well as feed airplay into the hifi.

The setup for the later configuration is extend wireless.. the configuration however could be to join a wireless network which will not extend. So you would need to pick the right one.

Extend wireless is very poor though.. and especially if both boxes are next to each other.. you might find the express is ok for airplay on hifi but will not handle video streaming which requires a lot more bandwidth.

So easier to ask a few questions.

1. What is make and model of your main wireless router?

2. It would be much better to use ethernet or even powerline adapters to get network to your TV location. Powerline adapters can work very well.

3. If you really need to use the Express to extend wireless.. what model is it? Using it inside TV cabinet is really poor.. it should be half way between the TV and the main wireless router.. it must pickup good signal to extend good signal. That means you might not be able to use it for airplay.. but perhaps you can use the TV4.

Router is an Apple Time capsule 2nd Gen

Very old and poor wireless.. so that is not going to help.

I've not thought of Powerline adaptors before .. but a bit of research tonight following your response has got me thinking that I ought to invest

They can work great or not at all or anywhere in between. If the two outlets are on the same ringmain it can work very well.. the packs with two units.. AV500 type are not over expensive but it might be worth it to either buy second hand or buy from a retailer who accepts returns. The companies selling these are almost as great liars as those selling wireless gear. And the higher speed you go.. the bigger the lies.. ie AV2000 might cost 4x the price of AV500 and get twice the speed or less..

Test the outlets in your house.. remember the powerline adapter should be plugged directly into the wall. Powerboards cannot be used with them. (although this is more or less true depending on a number of things).

Use a simple light plugged into power outlet and drop the breaker or pull the fuse .. determine which outlets (rooms) are associated with each fuse.. Do this while you are not going to annoy other people as they tend to get might upset when the TV drops out etc. Pick two outlets you know are behind the same fuse.

D-Link has software available (PC only of course) to actually check the sync of the units.. so you can see which unit is having problems.

Correction to my earlier post: the TC is a 4th gen model.

Ok.. Gen4 is a much better unit.. although it is getting to end of service life. The wifi output should be still fairly high.. but use the tools .. wireless diagnostics in the Mac to check it.

ten 16amp power circuits

Either you live in a massive house or a very old house.. ringmain is newer method of wiring.. in the olden days they would just wire specific areas.. this is much worse for EOP powerline. However if your fuse box is still old fashioned fuses and not modern breakers.. then that is advantage. Having more than single phase is a huge disadvantage.. generally they cannot talk across phases.