Error -1688 while logging in via NMAS Radius

Error -1688 appears on the Radius console screen, or on the Radius Debug console screen after enabling RADIUS debugging.

The -1688 error code is an NMAS error code identifying concurrent logins. To correct this issue, increase the number of allowed concurrent logins.

Each additional service loaded over the RADIUS connection may also require a connection. When implementing the NMAS Radius service, it is suggested to allow two or more concurrent connections. A single connection may only allow the RADIUS authentication to succeed but other services (e.g. mapping a network drive over a dial-up or VPN connection) to fail.