Powerline 1200 Adapter Problem

Hello,

I recently purchased four Powerline 1200 adapters for my home to improve network coverage (there are a number of wifi dead spots). I have one adapater upstairs attached directly to a router, while the other three are located downstairs. I observe the following problems with each of the downstairs adapters:

1. The Powerline LED (bottomost indicator) continiously switches from green to red. It seems to work reasonably well most of the time despite this fact.
2. Occasionally the adapter drops network connectivity briefly and then reconnects, which can be a problem for certain scenarios (online gaming, etc.).
3. Even less frequently, the adapter stops working entirely and the Powerline LED goes solid red. The only way I can resolve this is by unplugging the unit and plugging it back in (which works immediately).

The above problems occur regardless of which adapter I'm using (out of the four I purchased) or which power outlet I plug them into. All adapters are plugged directly into walls (no power strips or the like). I'm not using the encryption feature on any of them.

Does this likely mean that my power lines are simply too noisy for this product to work adequately? Are there any other simple troubleshooting steps I might try before abandoning them?

- Mark R.