We're having trouble with two black Roku sticks. The first one, which we bought on Amazon, worked fine for a few weeks but then had problems connecting to Netflix or other channels. We tried resetting network settings, restarting the Roku, and doing hard resets, but nothing seemed to work.

We eventually sent a message to Amazon and received a replacement. It seems to have similar problems. Currently, it freezes at some point in the setup process: either when connecting to the network or when getting the access code.

Our wifi network works fine and fast otherwise, with several laptops and phones. We've tried moving the TV to a spot that seems to have a stronger connection, but that didn't work.

We'd appreciate any ideas or steps you might suggest.

do you have another tv you can try the stick on? I am thinking that the tv it is attached to is interfering with the wifi 

See the second sticky about port installation or wifi problems.  Roku will basically send you an HDMI extender to help with wifi issues.