Time Capsule won't join existing network

Nonsense.

The problem is with the Airport utility.

The new versions will not allow you to do it but I have just used Airport 5.4.2 on a Hackbook running OSX 10.5.8 and connected a new Time Capsule to an existing wifi network provided by my BT router.

Get an old Macbook.

Good luck

If you really are happy with backups taking twice as long as normal, with twice as much of a chance of an error occurring in the process, and with no official support from Apple in the event of problems, then go for it. Good luck.

Sorry, but the Time Capsule cannot "join" or "extend" a wireless network provided by a 3rd party router. It must connect to a 3rd party router using a permanent, wired Ethernet cable connection......just as the illustration in the Setup Guide confirms.

However, if you have another Apple router......an AirPort Express, AirPort Extreme, or another AirPort Time Capsule.....the Time Capsule can wirelessly join and "extend" the signal provided by the other Apple router.

If the Ethernet solution is satisfactory to you, go with it. It takes the router-to-Time Capsule traffic off the WiFi an onto a more reliable, dedicated, and probably faster (especially if the router supports gigabit) connection. This is exactly how I have had my home network set up for years. My 5GHz SSID is the same on both the router and bridged TC. This is called a "roaming" network - use that terminology if trying to explain to someone rather than "extending the wireless network", which implies a WiFi connection between the networking devices. My 2.4GHz SSIDs differ for "historical reasons" 🙂 .

I'm pretty sure my airport express at home can extend (or at least join) wifi from my third party router.

The Express can "join" virtually any wireless network since Apple designed it to be used with other networks for use with AirPlay.

I thought the TC would be equally if not more capable.

The AirPort Express has an AirPlay function....and the Time Capsule does not.....the AirPort Express is special in that it can join a third party network......but it cannot "extend" a third party network.

Several years ago, using a different version of AirPort Utility and earlier firmware on the Time Capsule.....it was possible to configure the Time Capsule to "join" a network. But, since this is the worst possible way that a Time Capsule can be configured, Apple removed that option several years ago to improve performance.

When the Time Capsule did "join" a network, it produced what is known as a "double hop" wireless situation. By that, I mean that when your Mac was backing up, the signal had to go all the way back to the main router......hop one.....and then travel all the way back again from the main router to the Time Capsule.....hop two.

As you might imagine, this doubles the time that it takes for a backup to occur and doubles the changes of an error occurring in the process.

Also the setup is misleading because it gives you the option to try and join a 3rd party network.

Not that I can find using a current version of AirPort Utility.

Unfortunately I only read this when I realised that the 'Join Existing Network' option didn't work on the new TC I just bought. This is rubbish. I don't care if the techno heads think it's better to have this create the wifi network. I've had a previous 2TB TC on my network for four years now. No problem at all, no appreciable interference etc. Works like a dream, just got full.

I am NOT going to plug this into my excellent third party router and change over 3x iPhones, 3x iPads, 2x MacBook Airs, 2x ATVs, one additional speaker and an iMac because Apple decided to mess around with the specifications of what still is an originally an excellent concept.

But I'm going to buy a hard disk and plug it into my existing router, how about that? No need for a ridiculously expensive, poorly designed product! It's going back asap. Also the reviews on the Apple site are absolutely scathing.