I've got 3 sites all linked together via Senao SL-3054CB3 PLUS bridges (so that's 4 bridges). the short link is about 500m, using 8dBi Yagi antennas. It runs great, with FTP speeds of around 3MB/s.

The long link is about 5km, using 24dBi parabolic grid antennas. The Senaos report good "communication strength" (83% - about the same as the short link), but the link runs very slowly. FTP gets about 9kB/s. I've tried a whole range of channels, and some are worse than 9kB/s, but none are better.

The parabolic grids are the 2nd pair of antennas that I'm trying for the long link - the 1st pair was some 15dBi Yagis. The Senaos report better "communication strength" with the parabolic grids (up to 83% from about 73% with the Yagis), but both maxed out at 9kB/s FTP transfers.

There seems to be a short burst of higher transfer speed (maybe up to 20kB/s) in the first second or two of the FTP transfer, but then it comes down to about 10kB/s and eventaully settles around 9kB/s.

The Senaos on the long link are set to "802.11b only" - they seemed to run slower on mixed b and g mode, or g mode only.

Does anyone have a clue why the short link is working so well and the long one is so bad, when they both have the same "communication strength" according to the Senao's? Any ideas on how to fix it?

Since I've swapped the antennas already, I'm thinking of trying out a pair of Netgear bridges instead of the Senaos. Has anyone else got a long range link (around 5km or more) running at a good speed? If so, what equipment are you using?

Thanks for any help.