Snmpd define fix ID

With my OpenWrt 18.06.5 I installed snmpd (not mini-snmpd).

A new WLAN password is generated at 3 o'clock in the morning and activated with "uci commit" and "/etc/init.d/network relaod".

If I then use snmpwalk, the line
"IF-MIB :: ifDescr.42 = STRING: wlan0" has changed to
"IF-MIB :: ifDescr.52 = STRING: wlan0".

It seems that the ID always increases by 10, i.e. from 32 to 42, from 42 to 52 and so on.

How can I control that the interface number always stays the same?

I believe the kernel manages the interface numbers. I’ve never tried to “manage” them. You may need to use the interface name and index back to the current interface number.