Network samples?

It seems that payload error is linked to too short time between turn on wifi and joinNetwork. I put a Thread.Sleep(2000), and payload seems have gone.
But Buffer size error continues to appear randomly.

As previously said, I can update time of FEZ correctly but can’t get a web page with TestHttp (for now I Don’t try https). Code is below.

I get this:

## Start test...
Failed allocation for 52 blocks, 832 bytes

    #### Exception System.Exception - 0x00000000 (1) ####
    #### Message: Request failed
    #### GHIElectronics.TinyCLR.Networking.SPWF04Sx.SPWF04SxInterface::GHIElectronics.TinyCLR.Net.NetworkInterface.IDnsProvider.GetHostByName [IP: 004f] ####
    #### System.Net.Dns::GetHostEntry [IP: 000b] ####
    #### System.Net.HttpWebRequest::EstablishConnection [IP: 00e4] ####
    #### System.Net.HttpWebRequest::SubmitRequest [IP: 0019] ####
    #### System.Net.HttpWebRequest::GetResponse [IP: 000c] ####
    #### testWifi.App::TestHttp [IP: 0049] ####
    #### testWifi.App::Init [IP: 00e7] ####
    #### testWifi.App::.ctor [IP: 000a] ####
    #### testWifi.Program::Main [IP: 0005] ####
    #### Exception System.Net.WebException - 0x00000000 (1) ####
    #### Message: 
    #### System.Net.HttpWebRequest::GetResponse [IP: 00d3] ####
    #### testWifi.App::TestHttp [IP: 0049] ####
    #### testWifi.App::Init [IP: 00e7] ####
    #### testWifi.App::.ctor [IP: 000a] ####
    #### testWifi.Program::Main [IP: 0005] ####
Exception levée : 'System.Net.WebException' dans GHIElectronics.TinyCLR.Networking.Http.dll

WIND: SocketClosed 0:0