You should really start with the example, and then change as little as possible. If the default doesn't work, then the default is wrong. But if the default works and your changes break it, well... you know what happened.
When you start off by changing random things and "it doesn't work", then you have no idea what the problem is.
Actually I have started with the default configuration, but it did not work. Here is a diff of the two changes I did compared to master: @@ -38,7 +38,7 @@ # use the same interface. So it is defined here once, and used # below. # - interface = en0 + interface = eth0 # # port:: The port where we accept packets. @@ -197,7 +197,7 @@ # "link local" address on that interface, # and use that as the value for `ipaddr`. # -# ipaddr = 2001:db8:: + ipaddr = 2001:3200:3200::10 port = ${...port} interface = ${...interface} I've got this error: freeradius | Mon May 29 13:51:10 2023: Debug : Loaded module proto_dhcpv6_udp freeradius | Mon May 29 13:51:10 2023: Debug : udp { freeradius | Mon May 29 13:51:10 2023: Debug : ipaddr = FF02::1:2 freeradius | Mon May 29 13:51:10 2023: Debug : interface = eth0 freeradius | Mon May 29 13:51:10 2023: Debug : port = 547 freeradius | Mon May 29 13:51:10 2023: Debug : networks { freeradius | Mon May 29 13:51:10 2023: Debug : } freeradius | Mon May 29 13:51:10 2023: Debug : max_packet_size = 8192 freeradius | Mon May 29 13:51:10 2023: Debug : max_attributes = DHCPV6_MAX_ATTRIBUTES freeradius | Mon May 29 13:51:10 2023: Error : /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[93]: Invalid value "DHCPV6_MAX_ATTRIBUTES" for config item max_attributes: Failed parsing string as type 'uint32' freeradius | Mon May 29 13:51:10 2023: Error : /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[93]: Failed evaluating configuration for module "proto_dhcpv6_udp" freeradius | Mon May 29 13:51:10 2023: Error : /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[65]: Failed evaluating configuration for module "proto_dhcpv6" freeradius | Mon May 29 13:51:10 2023: Error : /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[65]: Failed parsing config for listener So I've added: max_attributes = 200 to the udp part of both listeners (it's probably possible to set the DHCPV6_MAX_ATTRIBUTES somewhere, but an environment variable did not work, so I've set it directly. Then it threw this error: freeradius | Mon May 29 13:57:23 2023: Error : Duplicate proto_dhcpv6 instance "dhcpv6.dhcpv6", previous instance defined at /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[65] So I thought having two listeners without name is not allowed, so I have added names to both (hence multicast and unicast) This finally made it to work in a way that the server starts - no errors, only these warnings: Mon May 29 14:01:43 2023: Warn : trigger { ... } subsection not found, triggers will be disabled Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[793]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[809]: Ignoring "-ldap" as the "ldap" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[1115]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[1228]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[1443]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[978]: Ignoring "-ldap" as the "ldap" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/default[80]: radius { ... } section is unused Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[212]: dhcpv6 { ... } section is unused Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/dhcpv6[301]: send Offer { ... } section is unused Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/inner-tunnel[124]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/inner-tunnel[134]: Ignoring "-ldap" as the "ldap" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/inner-tunnel[267]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : /opt/freeradius/etc/raddb/sites-enabled/inner-tunnel[302]: Ignoring "-sql" as the "sql" module is not enabled. Mon May 29 14:01:43 2023: Warn : src/lib/server/virtual_servers.c[311]: radius { ... } section is unused Mon May 29 14:01:43 2023: Warn : inner-eap - Failed to find 'authenticate inner-eap {...}' section. EAP authentication will likely not work Mon May 29 14:01:43 2023: Warn : tls - A virtual_server must be provided for stateful caching. cache.mode = "auto" rewritten to cache.mode = "stateless" Mon May 29 14:01:43 2023: Warn : tls - A virtual_server must be provided for stateful caching. cache.mode = "auto" rewritten to cache.mode = "stateless" but it does not process the requests, this is the only output I get when I run the dhclient: on May 29 14:01:43 2023: Debug : Scheduler created in single-threaded mode Mon May 29 14:01:43 2023: Debug : #### Opening listener interfaces #### Mon May 29 14:01:43 2023: Debug : Listening on radius_udp server * port 1812 bound to virtual server default Mon May 29 14:01:43 2023: Debug : Listening on radius_tcp server * port 1812 bound to virtual server default Mon May 29 14:01:43 2023: Debug : Listening on radius_udp server * port 1813 bound to virtual server default Mon May 29 14:01:43 2023: Debug : Listening on dhcpv6_udp server ff02::1:2 port 547 on interface eth0 bound to virtual server (null) Mon May 29 14:01:43 2023: Debug : Listening on dhcpv6_udp server 2001:3200:3200::10 port 547 on interface eth0 bound to virtual server (null) Mon May 29 14:01:43 2023: Debug : Listening on radius_udp server 127.0.0.1 port 18120 bound to virtual server inner-tunnel Mon May 29 14:01:43 2023: Info : Ready to process requests Mon May 29 14:05:23 2023: Debug : proto_dhcpv6_udp - Received Solicit XID 00e92f3c length 56 dhcpv6_udp server ff02::1:2 port 547 on interface eth0 Mon May 29 14:05:23 2023: ERROR : (0) ERROR: Virtual server "(null)" not compiled Mon May 29 14:05:23 2023: ERROR : (0) ERROR: Protocol failed to set 'process' function Mon May 29 14:05:23 2023: Debug : proto_dhcpv6_udp - cleaning up request in 5.000000s Mon May 29 14:05:23 2023: Debug : proto_dhcpv6_udp - Received Solicit XID 00566cdf length 56 dhcpv6_udp server ff02::1:2 port 547 on interface eth0 Mon May 29 14:05:23 2023: ERROR : (1) ERROR: Virtual server "(null)" not compiled Mon May 29 14:05:23 2023: ERROR : (1) ERROR: Protocol failed to set 'process' function Mon May 29 14:05:23 2023: Debug : proto_dhcpv6_udp - cleaning up request in 5.000000s Mon May 29 14:05:28 2023: Debug : TIMER - proto_dhcpv6_udp - cleanup delay Mon May 29 14:05:28 2023: Debug : TIMER - proto_dhcpv6_udp - cleanup delay Ludo