Hi We have a problem at my Bridge club where we use Android tablets to send the result of a hand to the scoring PC over wifi to an access point, then to the scoring PC. The PC then sends feedback to the tablet. Occasionally a tablet has a problem getting feedback. We find that sometimes turning wifi off and on will allow a tablet to get feedback but it usually goes wrong again soon after. The problem is random across all tablets. I captured a wireshark log at the scoring PC and it shows that a tablet that is struggling to get feedback is sending a TCP connection reset (RST) right at the start of the TCP transaction e.g. - (source port is 57727)
2136.258745 192.168.1.58 192.168.1.10 57727 -> 9000 [SYN] Seq = 0 2136.258893 192.168.10.1 192.168.1.58 9000 -> 57727 [SYN,ACK] Seq = 0 2136.354344 192.168.1.58 192.168.10.1 57727 -> 9000 [RST] Seq = 1 2137.256806 192.168.1.58 192.168.10.1 57727 -> 9000 [TCP Retransmission] Seq = 0 2137.256901 192.168.10.1 192.168.1.58 9000 -> 57727 [segment not captured, port numbers re-used] 2136.354344 192.168.1.58 192.168.10.1 57727 -> 9000 [RST] Seq = 1
Often the TCP reset comes back really fast - 3 milliseconds e.g. 2254.954148 192.168.1.58 192.168.1.10 54281 -> 9000 [SYN] Seq = 0 2254.954254 192.168.10.1 192.168.1.58 9000 -> 54281 [SYN,ACK] Seq = 0 2254.957301 192.168.1.58 192.168.10.1 54281 -> 9000 [RST] Seq = 1
I've compared the [SYN,ACK] sent by the PC against a successful one and there is no difference. Does anyone have an idea what could cause this? The tablets are Lenovo TB3 710F. The capture file is here pcap file
