I have a problem with my wireless connection, which drives me nuts.
I have been testing with two different wireless usb adapters, one based on the ar9271- and the other rtl8192su-chipset, but they both give same result.
The wireless usb adapters are connected to an open embedded linux kernel 2.6.32, running on a custom board with an ARM9 CPU.
The link is configured in adhoc-mode, and connected to an Windows 7 pc.
The problem is that I cannot transfer large files via the wifi link, I have testet with both Samba and vsftpd, but no difference.
I have testet the link using iperf (both TCP and UDP), successfully transferring about 5Gbytes of data. But if I try to transfer a file using samba or vsftpd the link drops within a minute (less than 20Mbytes).
When the connection drops it still seems "connected" in both ends, but nothing works, not even ping.
If I do an "iw wlan0 scan", the only station that appears is my own network.
I cannot find anything usefull in /var/log/ I tried dmesg, but that did not give anything either.
How do I debug this problem? I need to find out where and why in the wireless-stack the problem is caused.
UPDATE: If I run iperf with the -d option as suggested below, I get the describer problem. So it seems to have something to do with bidirectional data communication. In wireshark I see: TCP Retransmission, TCP Dup Ack
UPDATE: After the failure, if I do "iw wlan0 scan" only my own network appears...