Apple recommends using the same service-set identifier (the name for a wireless network) for both the 2.4GHz and 5GHz bands, saying the client will intelligently detect the band by itself and, if it supports both bands, it will pick the 5GHz over the 2.4GHz band. In our tests, this worked with a MacBook Pro -- the laptop immediately picked the 5GHz band every time.
Using a Windows-based system was a different story. Our Windows laptop, which supports both 5GHz and 2.4GHz wireless n, picked the 2.4GHz every time. We couldn't figure out why this happened, and the router wouldn't let us manually set the machines to use the 5GHz band to take advantage of the higher throughput speeds.
For this reason, we would recommend always having a separate wireless-network name for each band so you can have more control over which band you connect a client to. The 'wireless option' button in Airport Utility allows you to do this.
Unfortunately, although you can choose to turn off the wireless function of the router altogether, you can't turn off either of the bands separately. This means getting the router to work with 2.4GHz only or 5GHz only is impossible.
All other true dual-band routers we've reviewed allow users to have more control over the router's wireless functionality. In many situations, you'll want to use only the 5GHz band and turn the 2.4GHz band off to save power or keep the spectrum cleaner for other devices. You simply can't do this with the Time Capsule.
You have even less control over the Time Capsule's 'guest networking' feature, which lets you create a separate wireless network that has access to the Internet but not to local resources, such as your computer or printer. The feature worked well in our tests, but we found its functionality somewhat limited. All you can do is turn on or off the guest network, change the network's name, apply encryption to it, and give guest clients the ability to interact with one another. The Time Capsule doesn't let you choose which band you want the guest network to operate in, nor does it allow you to make a separate guest network for each band.
You'll need to install Bonjour on any Windows-based machines that you want to share the printer or the Time Capsule's storage, which is a hassle. You'll also want to check ahead of time to make sure your printer supports Mac. Set-up with some printers didn't go smoothly in our tests.
When we plugged the HL-1850 in using the USB connection, the Time Capsule didn't react at all. The SCX-4100 was recognised by the router, but there's no Mac version of the printer's software driver. Nonetheless, we think it would have been easy to install if there had been a driver, as the printer did appear in our MacBook Pro's 'print and fax' utility.
Other routers we've reviewed, generally have much better support for printers. For example, the D-Link DIR-825 worked with virtually every USB printer we tried it with. We didn't try the D-Link with these two printers, however, as they weren't available at the time of our review.
The Time Capsule's support for USB external hard drives is much better than for USB printers, and better than the Base Station's support, as well. It's still far from perfect, though.
The Time Capsule doesn't read drives formatted in the NTFS file system -- only files formatted as FAT32 and Mac OS Extended. In general, it's more difficult to format a drive larger than 32GB using FAT32 than it is using NTFS. This means that, because the majority of external hard drives nowadays are much larger than 32GB, Windows users can't simply plug most of their USB external hard drives into the router and expect to share the data contained on them. If you are willing to reformat your hard drive, you'll need to use a computer to do so, as Time Capsule doesn't include a formatting function.
Unlike the Base Station, the Time Capsule quickly recognised our external hard drive formatted using FAT32, and it worked as well as when it was formatted in the Mac OS Extended file system. Once our drives were plugged in, the Time Capsule instantly recognised and started sharing them. Sharing worked well in Windows, too.
The hard drives can be shared only as one shared folder, however. You can't make multiple folders and share them separately with different access privileges, which is a common NAS feature. You can, however, use AirPort Utility to create user accounts that each have a private folder of their own.
The Time Capsule's internal hard drive allows you to erase its content or manually archive it to an external hard drive. You can also change the default share name to whatever you like. Unfortunately, you can't physically access or replace the hard drive yourself. Most of the NAS servers we've reviewed, and even some external hard drives, allow users to replace internal hard drives.