PAN9026 drivers and /etc/network/interfaces
I have compiled the PAN9026 driver, loaded the drivers by insmod command and then I'm able to use the two new interfaces (mlan0 and uap0).
But if I edit the /etc/network/interfaces file these two interfaces disappear from the network interfaces listed by ifconfig command.
Ho can I fix this my problem?
Please note that the uap0 and mlan0 interfaces provided by the PAN9026 driver are completely regular Linux network interfaces.
So whatever you are trying to achieve is not specific to PAN9026, but could work or not work with any other network interface on your system.
Network device handling in Linux systems has changed a lot over time. Traditionally /etc/network/interfaces was used, but this approach has been superseded by using more sophisticated tools like NetworkManager, which - for example - can handle dynamic changes to the network infrastructure automatically.
You did not share enough information about the system you are using, so I can just guess. Do you have NetworkManager running in the background?
If so, it could be that NetworkManager automatically picks up the interfaces and "downs" them, because the configuration may be incomplete or missing.
In that case "ifconfig" will not show them anymore, but "ifconfig -a" will.
Anyway, as said above, the situation is not specific to PAN9026, but it is a generic Linux networking configuration problem.
Please check out the necessary documentation for the system you are using to check how network interfaces can and should be configured in that environment.