Recently,
we attempted to update the freeradius from version 2.x to 3.2.6.
We copied the existing configuration(clients.conf, radiusd.conf etc) to the freeradius installed on the new Linux system.
In testing, there were no issues with PPP that directly requests authentication from the cpe to the radius server.
However, L2TP authentication that passes through another company’s proxy radius encounters an error.

The error message is as follows.

Auth: (207) Login incorrect (chap: &control:Cleartext-Password is required for authentication): [[email protected]] (from client PhibeeProxy2 port 16777956)

There have been no changes to the IP and password of the other side in clients.conf.

I read the relevant information about PAP and User-Password in the migration documentation. All passwords are set as Cleartext-Password

If anyone has experienced a similar issue, any advice would be appreciated