Android WLAN roaming breakage

We have two access points at home, and wireless clients can roam freely, keeping their IP address.

Most clients can. Android phones and tables could not. For example, if a Motorola Xoom (Android 3.0) was in range of both APs, then it would switch to the other AP every 3-4 seconds.

The problem was that one AP was set to support only 802.11g, while the other was set to support b/g. Setting both to G-only solved the problem. The Xoom now connects quickly and keeps its connection (so long as it remains still at least).