Mac – connect the Time Capsule wirelessly to the mobile router

Your Time Capsule is not successfully connecting to the router.

1. If possible, move the Time Capsule to the same room as the router until you've got it working properly.
2. From within Airport Utility, check for software updates.
3. Connect your computer to the Time Capsule with an Ethernet cable. Be sure NOT to use the WAN port on the Time Capsule for this connection.
4. Go through the MANUAL setup and check each detail carefully. Save the configuration and let it restart, then if not working, report all settings/messages here. You should be able to see the settings still because you're connected via the cable.

EDIT: Have the Time Capsule join the existing network, not extend the network, at least as a first step, as some routers can be configured to disallow extending their networks.

I asked the same question on the Apple forums, and got a solution that worked for me:

https://discussions.apple.com/message/20182532?ac_cid=op123456#20182532

I'll repeat it here so somebody else might find it useful in the future:

This is where you use a roaming network.

Do not extend.. that is much slower.. since you have ethernet and the TC plugged in you are 90% of the way there.

Use the TC to create a network.. with the same name and same passkey with security settings as the wireless downstairs. Locking channels is not a bad idea.. as this does require one difference .. the network upstairs must be on a different channel to the one downstairs.. then all will be hunky dorey.. !!