Where I got to with the WiFi shield.
Summary: The shield is usable for sending/receiving small UDP packets most of the time, but not much else.
Issues:
- The 90 byte transfer limit is annoying but not game breaking, Throughput appears to be bottlenecked further by a polling loop in the order of seconds.
- During long running UDP tests (days), some transient event I have yet to identify, places the shield into a stalled state, with none of the software gymnastics I have tried, able to recover or restart it. The transient event may have something to do with roaming across access points and expiring authentication tokens.
- The TCP implementation is completely borked, from the layer 7 Sockets implementation, down to the sequencing of SYN/FIN/RST/ACK packets at layer 4. The shield will just about work as a TCP client, providing the server can tolerate orphaned sessions.
The state of the firmware leaves the shield being too broken to be much use to me. Fixing the firmware is beyond the time, knowledge and resources I have available. So the very best of luck with it.
I have since acquired a Yun.