I was testing 8.09 from November til last week on AR71xx and IXP4xx boards (Mikrotik RB433AH and Sparklan WAPD-170AG) each with 1 miniPCI Atheros card in it. It was working great. Madwifi, quagga, ssh, and nothing else. Worked like a charm, 7.5 MB/s throughput on SuperA link, everything I need.

After that I bought more miniPCI cards and tried to run more links on it, but I have problems...

1 link is working perfectly. Still having 7.5MB/s over it. Same on both boards, the first link works like on my old routers.
The second link is working, but the signal level is cca 9dBm lower than before (Debian based PC with a Trendnet PCI ABG wireless card). But, the other side of the link receives the OpenWRT's wireless card with 16-18 dBm lower signal than before.

The same problem apears on both RBs (different archs, both Kamikaze 8.09), with different cards (Mikrotik R52 and some miniPCI from e-bay with the same chipset as R52). I also tried to switch links, but then I get the same problem, but switched. The link that had -58dBm at both end gets -66dBm at OpenWRT and -75dBm at the other end (Debian PC router).
The link is still up, but I cant get more than cca 500 KB/s over it. That throughput matches the signal level and Link Quality displayed on the Debian box (Signal -75, LQ 20).

Any ideas whats going on? What to try next?