Help set up 3TB Time Capsule without LAN access to router?

Is there a way to do this configuration via wifi only?

Not unless the main router is apple. Apple extend is proprietary and will not work on other brands.

If you wish to use wireless you will need a wireless bridge.. so that you can plug the TC into ethernet connection and can then create a wireless network.

The airport express can do this.. and only the express out of apple's router lineup.. but there are plenty of cheaper bridges out there.

It is best to select something that is known to work well with the modem router your neighbour is running.

The wireless bridge operates just like a "modem" on a normal network.

The TC needs to stay connected to the "modem" at all times.

If you do not want your neighbor to have access to (be able to see inside) your network, I recommend using a wireless bridge as recommended above, plugging the Ethernet connection into the WAN port, and then configuring the router mode in Airport Utility as "DHCP and NAT". It will probably give you a warning about "double NAT" but that is fine.

This way, if you have a network printer, an Apple TV, or some other advertised resource on your network, you do not have to worry about your neighbor using it. Unless that IS what you want, in which case you'd want to configure in Bridge mode (with some neighbors I'd be OK on this; others not so much).

used an old wallplug Repeater Ethernet connected to the TC with Create a New Network and DHCP and NAT on.

A wireless repeater is useless.

You must have a wireless bridge (some repeaters do both)..

It must pick up a wireless connection to the main router.. and then allow the TC to connect to it..

However this piece of advice is .. hmm.. not 100% correct..

and then configuring the router mode in Airport Utility as "DHCP and NAT". It will probably give you a warning about "double NAT" but that is fine.

The problem is if the main router is 10.x.x.x and the TC is default to 10.x.x.x it won't work. Double NAT also has any number of issues. It is not wrong.. it is just not going to work in 100% of cases.

I would prefer you to setup the TC in bridge..

You still need to create a wireless network.. with a different name to the main router.

Anyhow give us a screenshot straight from the airport utility .. click on the TC to show us the summary page.

From that we can usually figure out what is going wrong.

The TC needs to be part of the network to give you internet and backup at the same time.

Given the (lack of) security savvy I see on an almost daily basis, I'd hesitate from just recommending a bridged setup without at least some discussion of the security issues. When I read or hear about these neighbor-sharing arrangements, I wonder if either party has thought about - or is even aware of - the risks involved. It is more than just "how well do you know your neighbor" as I said above. What equipment does the neighbor have and is it configured correctly (e.g. have they punched any holes in their firewall)? Does the neighbor participate in any online activity that could attract the interest of "authorities" - and implicate you based on the fact that you are directly attached to the network. etc.

Personally, unless it were a close relative or friend and I had a direct hand in setting up and maintaining the neighbor network, I'd prefer to deal with the double-NAT issues. And in any case, it would only be a temporary situation as I'd get my own service installed ASAP.

Any legal implications of what people are doing rests solely on the person who pays the account. They might claim someone is using their internet wrongly but it is the owner's responsibility to ensure people do not use it wrongly. If I was the owner.. I would be very concerned at offering GUEST access.. because even double NAT is not stopping anyone from downloading what they shouldn't. Copyright or plainly illegal stuff.

Apple routers with their amazing soft reset.. which removes all passwords for 5min means the moment you step out the door.. any savvy person can reset your router.. find out your passwords and even do some tricky route setups for the super smart.. and you won't even know because there is no logging of the access.

Maybe though you are being just a bit paranoid??

As a tenant getting access via the owner I really think it is pretty ok.. and since owner has full access to tenant's stuff any time the tenant goes out maybe secure passwords on the devices themselves are better idea than over worrying about double NAT.

Anyway.. from technical side many routers use 10.x.x.x IP and if the WAN and LAN IP are in the same range.. whole A class is assumed .. it cannot route.

So it does make it a bit more complicated to the novice to setup.

They might claim someone is using their internet wrongly but it is the owner's responsibility to ensure people do not use it wrongly.

Some folks I know who got visits from the Secret Service due to a joke one of them played a few years ago might disagree with you. At least no one went to jail, but it was more stress than any of them really wanted to deal with.

As a tenant getting access via the owner I really think it is pretty ok.

But given the scant information given by the original poster ("we use the neighbor's wifi router with the password she gave us") do you feel comfortable just saying "I would prefer you to setup the TC in bridge" with absolutely no mention of the risks?

Some folks I know who got visits from the Secret Service due to a joke one of them played a few years ago might disagree with you. At least no one went to jail, but it was more stress than any of them really wanted to deal with.

How does double NAT protect you from the jokers.. ?? Sorry but if you live in a shared house and someone starts playing jokes.. or actual serious crime.. I doubt the secret service and all the agencies you have in the US.. are going to burst into the door and ask.. ok.. who was behind a double NAT.. you are ok.

Everyone in the house is equally suspect.. and packets from WAN do not show anything.

But given the scant information given by the original poster ("we use the neighbor's wifi router with the password she gave us") do you feel comfortable just saying "I would prefer you to setup the TC in bridge" with absolutely no mention of the risks?

Your list of what a neighbour is going to do..

This way, if you have a network printer, an Apple TV, or some other advertised resource on your network, you do not have to worry about your neighbor using it.

is hardly a big concern.. if they print to my printer .. is that a major security risk.. or run airplay to my appleTV..

Apple systems are pretty well protected.. unless a person has opened shares without a password.. what is it that people are going to access that I should be scared about??

If it was the person who owned the internet service.. then I would give plenty of warnings.. sharing your internet service has implications then sure.. I would give loads of warnings.. but as the person who is "renting" access.. I would say.. if you are share internet you share what is accessible.. !!

As far as sharing my printer or apple tv.. it is hardly a security breach.

Double NAT btw will not stop a serious hacker.. there are methods to get around it .. it might stop casual peeking.

Many people live in shared situations.. in our part of the world sharing internet is not uncommon.. we often have little choice given how poor access is here to decent broadband.. services can be denied because they changed policy one day. So your neighbour who is willing to share gets access and you get dial up.. Very few people run into problems.. but the person who needs protection is the service owner.