Some confusion about channels and frequencies

Yep, indeed. The 5GHz band is actually in 5 MHz chunks.
So the calculation is easy - Chan = (freq - 5000) / 5
In oid_mgt.c replace these lines (44 to 47) :

         } else if ((f >= (int) 5170) && (f <= (int) 5320)) {
                 while ((c < 12) && (f != frequency_list_a[c]))
                         c++;
                 return (c >= 12) ? 0 : (c + 37);

with :
         } else if ((f >= (int) 5000) && (f <= (int) 6000)) {
                 return ( (f - 5000) / 5 );

This gives :
eth1      26 channels in total; available frequencies :
           Channel 34 : 5.17 GHz
           Channel 36 : 5.18 GHz
           Channel 38 : 5.19 GHz
           Channel 40 : 5.2 GHz
           Channel 42 : 5.21 GHz
           Channel 44 : 5.22 GHz
           Channel 46 : 5.23 GHz
           Channel 48 : 5.24 GHz
           Channel 52 : 5.26 GHz
           Channel 56 : 5.28 GHz
           Channel 60 : 5.3 GHz
           Channel 64 : 5.32 GHz
           Channel 01 : 2.412 GHz
           Channel 02 : 2.417 GHz
           Channel 03 : 2.422 GHz
           Channel 04 : 2.427 GHz
           Channel 05 : 2.432 GHz
           Channel 06 : 2.437 GHz
           Channel 07 : 2.442 GHz
           Channel 08 : 2.447 GHz
           Channel 09 : 2.452 GHz
           Channel 10 : 2.457 GHz
           Channel 11 : 2.462 GHz
           Channel 12 : 2.467 GHz
           Channel 13 : 2.472 GHz
           Channel 14 : 2.484 GHz
           Current Channel:11

Margit