no kde - musíš se přihlásit do routeru, je tam na to celé menu ohledně stavu DSL linky.

System monitor -> xDSL statistics

Zajímá tě "Line rate," případně "Attainable net data rate"

============================================================================
    xDSL Training Status:   Idle
                    Mode:   G.DMT 
            Traffic Type:   Inactive
             Link Uptime:   N/A
============================================================================
       xDSL Port Details       Upstream         Downstream
               Line Rate:      0.000 Mbps        0.000 Mbps
    Actual Net Data Rate:      0.000 Mbps        0.000 Mbps
          Trellis Coding:     N/A                N/A
              SNR Margin:        0.0 dB            0.0 dB
            Actual Delay:          0 ms              0 ms
          Transmit Power:        0.0 dBm           0.0 dBm
           Receive Power:        0.0 dBm           0.0 dBm
              Actual INP:        0.0 symbols       0.0 symbols
       Total Attenuation:        0.0 dB            0.0 dB
Attainable Net Data Rate:      0.000 Mbps        0.000 Mbps
============================================================================