My Time Capsule does not work with existing WiFi

Question

Following a question solved on March 24 by LaPastenague, but gone bad again.
Apple AirPort Time Capsule
I felt the need for a physical backup of my data, as I would not completely trust the different clouds. I use, and have used Dropbox for 4-5 years and are very satisfied with that, but I am still not sure if or when a political lunatic will shut off the internet.
I purchased the Apple AP Time Capsule 2T, because all my other stuff are Apple, and that it's wireless. My old backup is Maxtor 300 GB.
Since we stay 2-3 weeks on two locations, one in Norway and one in Sweden (two different countries) we must use Mobile Broadband 4G, cables or fibre connections are useless for us, and we don't have it up to the houses. I have one mini router for each country, we bring with us iPhones, iPads, iMac, Apple TV, APExpress. When we pass the boarder I change the mini router, and the system continues working perfect on the WiFi, except the APExpress that needs to be reconfigured,  but then it works.
The APTC was difficult to make working as it would not accept to be in an existing network, but with good help from the Apple Community, LaPastenague, with forcing the TC connect to the APE with Ethernet cable in bridge mode, ref "My Time Capsule does not work with existing WiFi" from March 24, the problem was solved and all gadgets worked together in a perfect harmony, until we changed location.
Now, as I have my second WiFi network, and the APExspress is reconfigured, it's like the TC thinks, I am the base boss here, I am not taking orders from APE one more time, and it simply does not work, not only that, it fluctuates all the time.
I have a slight feeling that the two WiFi bands are making the trouble as during the configuration of the TC sometime the last figure 6 and 7 pops up, and that has something two do with the two different 2,4 and 5 GHZ bands
So, I am curious if you have any idea ?
I am thinking of returning the TC if I don't make it work now, but how do I delete all the data that's on it?

Answer 1

I can deal with the last question first and easily.
I am thinking of returning the TC if I don't make it work now, but how do I delete all the data that's on it?
Open the airport utility .. go to the disk tab and select erase.
When you select erase you will get mulitiple options.
Quick removes the file table but does not delete the files,, it takes 2min or less.
A Zero out data is the secure way,, by writing 0 ie low level drive format.
It can take several hours..
7 pass will take a week.. not recommended..
35 pass erase is ridiculous.. it would take a month.. put an ax through the TC. It is quick and better.
Now, as I have my second WiFi network, and the APExspress is reconfigured, it's like the TC thinks, I am the base boss here, I am not taking orders from APE one more time, and it simply does not work, not only that, it fluctuates all the time.
The fact that it did work and has now failed might point to faulty unit.
The only way to tell is reset it properly to factory and start over.
Universal Factory Reset.. any model TC or AE.
Unplug your TC/AE from power or turn off at the power point.
Hold in reset. and power the TC/AE back on..  all without releasing reset and keep holding in for about 10sec. (this is often difficult without a 2nd person or a 3rd arm).
Release it when the status light flashes rapidly. If it doesn’t flash rapidly you have missed it and try again.
Note..
Be Gentle! Feel the switch click on. It has a positive feel..  add no more pressure after that.
TC/AE will reboot after a couple of minutes with default factory settings and will wipe out previous configurations of the router.
No files are deleted on the hard disk in a TC.. No reset of the TC deletes files.. to do that you use erase from the airport utility.
Generally having multiple wireless AP should not cause problems.. but it is better to set channels manually.. so it doesn't go beserk rotating channels.
Remember to keep all names short, no spaces and pure alphanumeric.
Sadly though the Apple routers have no logging now and no SNMP and almost nothing to help diagnose a problem, so if it continues .. take it back to apple.. they have given you no other method of fixing it.