#1
So here's my setup:
Main airport express downstairs in living room with modem. Second airport express extending the existing coverage upstairs in the office.
Can I connect a printer via usb to the second upstairs airport express and make it a wireless printer, or does it need to be connected to the main airport express downstairs?
Also, is it better to "extend network" vs. "join network"? What do I lose if I "extend the network"?
Also, am I correct in thinking that I can use BOTH airport express units for wireless airplay?
Are the two expresses wired together? If so, then the second airport should be set to "create a wireless network" and use the same SSID (network name) and password as the downstairs express. Wireless devices will simply connect to the one with the best signal.
If they are not wired together, then it depends on whether you want devices to wirelessly connect to the second express.
If you do, then you need to configure it as "extend a network." 1/2 the bandwidth will be used for upstream (to connect to the downstairs express) and 1/2 for devices that connect to it (the second express). (It's more fluid than 50/50, but that's the basic idea.) Thus, extending reduces the end to end speed. Also, if you extend then both expresses will be on the same channel. And since they must be in range of each other, it seems to me, then, that they will also interfere with each other, further reducing speed.
If you don't want devices to wirelessly connect to the second express, then you can set it as "join a network" and have it connect to the downstairs network. If you do this, then devices will not be able to wirelessly connect to it (the second express) and the ethernet port will be put in reverse - devices you connect to it over the ethernet port will be part of the network by using the second express to connect to the downstairs express. In other words, the ethernet WAN port will be turned into a LAN port.
You can connect the printer to either one.
Note that the ethernet port on the expresses is only 100mbps. Even if your internet connection is less than 100mbps, you would benefit by upgrading to gigabit for things like moving large files around on the network.
Finally, as a rule of thumb, for wireless connections, figure your transfer speeds will be roughly 2/3 the connect speed. So, if your device is connected at 300mbps, actual transfer speed will be about 200mbps, assuming no other bottlenecks. And that's assuming there are no other transmissions going on at the same time. Wireless bandwidth is shared.