Why is my Wi-Fi signal is suddenly weaker then it's ever been before

reyeuro,

firstly lets clarify what is a serious loss of signal strength.  Data rate dropping from 54 to 36mbps is a pretty minor change - if it had dropped to one tenth of the normal rate, then you would certainly notice it - as it is this drop of data rate will be barely noticeable unless you sit timing your file transfers with a stop watch!

I am not trying to play down your concern - rather to point out when things go wrong with a wireless network they will normally be far worse than you describe.    Something has changed in your network, so lets look at the possibilities.   There are two aspects to "loss of signal strength".  One is literally that the signal you want has got weaker - and the other (which Jon has concentrated on his answer) is that signals you don't want have become stronger, and are interfering with the signal you do want.

First lets be clear that you are not actually reporting a loss of signal strength - but rather a loss of data throughput.   The two are quite different, though you are right that a loss of radio signal strength will lead to loss of data throughput.   You also give us the only clue to what has changed - the application of WPA.    I agree with Jon that WPA will not affect signal strength - but it might well affect data throughput.  The obvious test for this is to remove it - and check your data throughput again.

If removal of WPA restores the data throughput to 54mbps, then it would indicate to me the link is marginal to your furthest rooms.    I am not an expert on the inner workings of WEP or 802.11 radio protocols, but I can guess that adding WPA provides a further load on the computing power of the radio system, and a link that is marginal *in radio terms* will be suffering from a lot of errors which need correction.   Addition of WPA may then just throw it "over the edge".

What to do about it?   Well, I personally would live with a drop from 54 to 36 mbps, as I outlined in my opening paragraph.   I wouldn't live without WPA in order to restore the full data rate!    What you can do is to try and increase the strength of your wanted signal, by:

-  making sure both aerials are installed on your Linksys wireless router (if it came with two)
- making sure that the aerials at both ends are not near anything else - i.e. don't let wires drap over them, keep them away from walls, etc
-  try changing the orientation of the aerials at either end and see if that improves things
-  try changing the position of the wireless parts at either end to see if that improves things.

To do the above tests, look to see if you have any wireless link "management software".   What you want is an indication of received signal strength so that you can judge the effect of any changes you make.  This is a much clearer indication than watching the download speed of data transfers.

Of course, WPA being applied or not may be entirely co-incidental, so we are back to other problems.  Loss of strength of your wanted signal could be due to:
- aerials at either end being moved in position or angle
- if your Linksys wireless router has two aerials supplied, one of them being removed (or loose)
- something being put near the aerials at either end
- a hardware fault
- a software fault

Checks for most of the above will be obvious.

Jon's answer has picked up on the other aspect - that of interference from other radio devices.   You neighbours may have also bought a wireless network, and you could be competing with them for radio space.   You can check fairly quickly by switching off your wireless router, and looking at the remote end for "all available wireless networks".   In some places, a very long list will appear!    If that is your situation, then there is little you can do, except be thankful yours is still working pretty well.  You can try changing the channel that your wireless router is using, and that may help in this situation.  The setting for this will be in the management software, but normally wireless routers try to find the clearest channel available, so you are unlikely to improve on that.

See Jon's answer for more details of dealing with interference.


best regards


Richard

Encryption, especially if you are using WPA with AES encryption is very processor intensive.
More processing creates more heat, more heat slows down processing.

Make sure you have good air flow around the router....i.e. nothing setting on top of its air vents,

Remove any recent changes and security see if you can get back 54 mbps, if yes, then recent changes are root causes. If not, see if there is any equipment or electronics device (microwave, cordless phones, sattelite disk, etc) that might cause interfere network.