You can set the requested prefix in the dhcp6 settings if that's what you're asking.
Your second attachment didn't upload correctly.
There's no need to put log files in a docx attachment. Doing that just means far fewer people will read it. You can attach .txt file which will open directly in the browser or just put the logs in code tags:
Aug 9 11:14:20 dhcp6c 11264 got an expected reply, sleeping.
Aug 9 11:14:20 dhcp6c 11264 removing server (ID: 00:03:00:01:dc:xx:xx:xx:xx:b7)
Aug 9 11:14:20 dhcp6c 11264 removing an event on igb0, state=REQUEST
Aug 9 11:14:20 dhcp6c 11264 script "/var/etc/dhcp6c_wan_script.sh" terminated
Aug 9 11:14:20 dhcp6c dhcp6c REQUEST on igb0 - running rc.newwanipv6
Aug 9 11:14:18 dhcp6c 11264 executes /var/etc/dhcp6c_wan_script.sh
Aug 9 11:14:18 dhcp6c 11264 failed to update an address 2a02:xxxx:xxxx:0:xxx:xxxx:xxxx:6938
Aug 9 11:14:18 dhcp6c 11264 failed to add an address on igb0: Invalid argument
Aug 9 11:14:18 dhcp6c 11264 create an address 2a02:xxxx:xxxx:0:xxx:xxxx:fe31:6938 pltime=3600, vltime=3915999254614645792
Aug 9 11:14:18 dhcp6c 11264 make an IA: NA-0
Aug 9 11:14:18 dhcp6c 11264 invalid prefix length 57 + 8 + 64
Aug 9 11:14:18 dhcp6c 11264 create a prefix 2a02:xxxx:xxxx:80::/57 pltime=3600, vltime=7200
Aug 9 11:14:18 dhcp6c 11264 make an IA: PD-0
Aug 9 11:14:18 dhcp6c 11264 nameserver[0] fd00::xxxx:xxxx:xxxx:3ab7
Aug 9 11:14:18 dhcp6c 11264 dhcp6c Received REQUEST
Aug 9 11:14:18 dhcp6c 11264 IA_PD prefix: 2a02:xxxx:xxxx:80::/57 pltime=3600 vltime=7200
Aug 9 11:14:18 dhcp6c 11264 get DHCP option IA_PD prefix, len 25
Aug 9 11:14:18 dhcp6c 11264 IA_PD: ID=0, T1=1800, T2=2880
Aug 9 11:14:18 dhcp6c 11264 get DHCP option IA_PD, len 41
Aug 9 11:14:18 dhcp6c 11264 IA_NA address: 2a02:xxxx:xxxx:0:xxx:xxxx:xxxx:6938 pltime=3600 vltime=7200
Aug 9 11:14:18 dhcp6c 11264 get DHCP option IA address, len 24
Aug 9 11:14:18 dhcp6c 11264 IA_NA: ID=0, T1=1800, T2=2880
Aug 9 11:14:18 dhcp6c 11264 get DHCP option identity association, len 40
Aug 9 11:14:18 dhcp6c 11264 unknown or unexpected DHCP6 option opt_86, len 16
Aug 9 11:14:18 dhcp6c 11264 get DHCP option opt_86, len 16
Aug 9 11:14:18 dhcp6c 11264 get DHCP option DNS, len 16
Aug 9 11:14:18 dhcp6c 11264 preference: 10
Aug 9 11:14:18 dhcp6c 11264 get DHCP option preference, len 1
Aug 9 11:14:18 dhcp6c 11264 DUID: 00:03:00:01:dc:xx:xx:xx:xx:b7
Aug 9 11:14:18 dhcp6c 11264 get DHCP option server ID, len 10
Aug 9 11:14:18 dhcp6c 11264 DUID: 00:01:00:01:24:de:xx:13:xx:xx:xx:x:xx:38
Aug 9 11:14:18 dhcp6c 11264 get DHCP option client ID, len 14
Aug 9 11:14:18 dhcp6c 11264 receive reply from fe80::xxxx:xxxx:xxxx:3ab7%igb0 on igb0
Aug 9 11:14:18 dhcp6c 11264 reset a timer on igb0, state=REQUEST, timeo=0, retrans=909
Aug 9 11:14:18 dhcp6c 11264 send request to ff02::1:2%igb0
Aug 9 11:14:18 dhcp6c 11264 set IA_PD
Aug 9 11:14:18 dhcp6c 11264 set IA_PD prefix
Aug 9 11:14:18 dhcp6c 11264 set option request (len 4)
Aug 9 11:14:18 dhcp6c 11264 set elapsed time (len 2)
Aug 9 11:14:18 dhcp6c 11264 set identity association
Aug 9 11:14:18 dhcp6c 11264 set IA address
Aug 9 11:14:18 dhcp6c 11264 set server ID (len 10)
Aug 9 11:14:18 dhcp6c 11264 set client ID (len 14)
Aug 9 11:14:18 dhcp6c 11264 a new XID (b29d1b) is generated
Aug 9 11:14:18 dhcp6c 11264 Sending Request
Aug 9 11:14:18 dhcp6c 11264 picked a server (ID: 00:03:00:01:dc:xx:xx:xx:xx:b7)
Aug 9 11:14:17 dhcp6c 11264 reset timer for igb0 to 0.998159
Aug 9 11:14:17 dhcp6c 11264 server ID: 00:03:00:01:dc:xx:xx:xx:xx:b7, pref=10
Aug 9 11:14:17 dhcp6c 11264 IA_PD prefix: 2a02:xxxx:xxxx:80::/57 pltime=3600 vltime=7200
Aug 9 11:14:17 dhcp6c 11264 get DHCP option IA_PD prefix, len 25
Aug 9 11:14:17 dhcp6c 11264 IA_PD: ID=0, T1=1800, T2=2880
Aug 9 11:14:17 dhcp6c 11264 get DHCP option IA_PD, len 41
Aug 9 11:14:17 dhcp6c 11264 IA_NA address: 2a02:xxxx:xxxx:0:xxx:xxxx:xxxx:6938 pltime=3600 vltime=7200
Aug 9 11:14:17 dhcp6c 11264 get DHCP option IA address, len 24
Aug 9 11:14:17 dhcp6c 11264 IA_NA: ID=0, T1=1800, T2=2880
Aug 9 11:14:17 dhcp6c 11264 get DHCP option identity association, len 40
Aug 9 11:14:17 dhcp6c 11264 unknown or unexpected DHCP6 option opt_86, len 16
Aug 9 11:14:17 dhcp6c 11264 get DHCP option opt_86, len 16
Aug 9 11:14:17 dhcp6c 11264 get DHCP option DNS, len 16
Aug 9 11:14:17 dhcp6c 11264 preference: 10
Aug 9 11:14:17 dhcp6c 11264 get DHCP option preference, len 1
Aug 9 11:14:17 dhcp6c 11264 DUID: 00:03:00:01:dc:xx:xx:xx:xx:b7
Aug 9 11:14:17 dhcp6c 11264 get DHCP option server ID, len 10
Aug 9 11:14:17 dhcp6c 11264 DUID: 00:01:00:01:24:de:xx:13:xx:xx:xx:x:xx:38
Aug 9 11:14:17 dhcp6c 11264 get DHCP option client ID, len 14
Aug 9 11:14:17 dhcp6c 11264 receive advertise from fe80::xxxx:xxxx:xxxx:3ab7%igb0 on igb0
Aug 9 11:14:17 dhcp6c 11264 reset a timer on igb0, state=SOLICIT, timeo=0, retrans=1091
Aug 9 11:14:17 dhcp6c 11264 send solicit to ff02::1:2%igb0
Aug 9 11:14:17 dhcp6c 11264 set IA_PD
Aug 9 11:14:17 dhcp6c 11264 set IA_PD prefix
Aug 9 11:14:17 dhcp6c 11264 set option request (len 4)
Aug 9 11:14:17 dhcp6c 11264 set elapsed time (len 2)
Aug 9 11:14:17 dhcp6c 11264 set identity association
Aug 9 11:14:17 dhcp6c 11264 set client ID (len 14)
Aug 9 11:14:17 dhcp6c 11264 a new XID (322b29) is generated
Aug 9 11:14:17 dhcp6c 11264 Sending Solicit
Aug 9 11:14:16 dhcp6c 11264 reset a timer on igb0, state=INIT, timeo=0, retrans=891
Aug 9 11:14:16 dhcp6c 10971 called
Aug 9 11:14:16 dhcp6c 10971 called
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>end of closure [}] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>end of closure [}] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[8] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[sla-len] (7)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[1] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[sla-id] (6)
Aug 9 11:14:16 dhcp6c 10971 <3>begin of closure [{] (1)
Aug 9 11:14:16 dhcp6c 10971 <5>[igb1.1] (6)
Aug 9 11:14:16 dhcp6c 10971 <3>[prefix-interface] (16)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[infinity] (8)
Aug 9 11:14:16 dhcp6c 10971 <3>[56] (2)
Aug 9 11:14:16 dhcp6c 10971 <3>[/] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[::] (2)
Aug 9 11:14:16 dhcp6c 10971 <3>[prefix] (6)
Aug 9 11:14:16 dhcp6c 10971 <13>begin of closure [{] (1)
Aug 9 11:14:16 dhcp6c 10971 <13>[0] (1)
Aug 9 11:14:16 dhcp6c 10971 <13>[pd] (2)
Aug 9 11:14:16 dhcp6c 10971 <3>[id-assoc] (8)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>end of closure [}] (1)
Aug 9 11:14:16 dhcp6c 10971 <13>begin of closure [{] (1)
Aug 9 11:14:16 dhcp6c 10971 <13>[0] (1)
Aug 9 11:14:16 dhcp6c 10971 <13>[na] (2)
Aug 9 11:14:16 dhcp6c 10971 <3>[id-assoc] (8)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>end of closure [}] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>comment [# we'd like some nameservers please] (35)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>["/var/etc/dhcp6c_wan_script.sh"] (31)
Aug 9 11:14:16 dhcp6c 10971 <3>[script] (6)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[domain-name] (11)
Aug 9 11:14:16 dhcp6c 10971 <3>[request] (7)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[domain-name-servers] (19)
Aug 9 11:14:16 dhcp6c 10971 <3>[request] (7)
Aug 9 11:14:16 dhcp6c 10971 <3>comment [# request prefix delegation] (27)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[0] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[ia-pd] (5)
Aug 9 11:14:16 dhcp6c 10971 <3>[send] (4)
Aug 9 11:14:16 dhcp6c 10971 <3>comment [# request stateful address] (26)
Aug 9 11:14:16 dhcp6c 10971 <3>end of sentence [;] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[0] (1)
Aug 9 11:14:16 dhcp6c 10971 <3>[ia-na] (5)
Aug 9 11:14:16 dhcp6c 10971 <3>[send] (4)
Aug 9 11:14:16 dhcp6c 10971 <3>begin of closure [{] (1)
Aug 9 11:14:16 dhcp6c 10971 <5>[igb0] (4)
Aug 9 11:14:16 dhcp6c 10971 <3>[interface] (9)
Aug 9 11:14:16 dhcp6c 10971 skip opening control port
Aug 9 11:14:16 dhcp6c 10971 failed initialize control message authentication
Aug 9 11:14:16 dhcp6c 10971 failed to open /usr/local/etc/dhcp6cctlkey: No such file or directory
Aug 9 11:14:16 dhcp6c 10971 extracted an existing DUID from /var/db/dhcp6c_duid: 00:01:00:01:24:de:xx:13:xx:xx:xx:x:xx:38
Aug 9 11:14:11 dhcp6c 60699 exiting
Aug 9 11:14:11 dhcp6c 60699 script "/var/etc/dhcp6c_wan_script.sh" terminated
Aug 9 11:14:11 dhcp6c 60699 executes /var/etc/dhcp6c_wan_script.sh
Aug 9 11:14:11 dhcp6c 60699 removing an event on igb0, state=RELEASE
Aug 9 11:14:11 dhcp6c 60699 script "/var/etc/dhcp6c_wan_script.sh" terminated
Aug 9 11:14:11 dhcp6c dhcp6c EXIT or RELEASE on igb0 running rc.newwanipv6
Aug 9 11:14:11 dhcp6c 60699 executes /var/etc/dhcp6c_wan_script.sh
Aug 9 11:14:11 dhcp6c 60699 status code: success
Aug 9 11:14:11 dhcp6c 60699 dhcp6c Received RELEASE
Aug 9 11:14:11 dhcp6c 60699 status code: success
Aug 9 11:14:11 dhcp6c 60699 get DHCP option status code, len 2
Aug 9 11:14:11 dhcp6c 60699 DUID: 00:03:00:01:dc:xx:xx:xx:xx:b7
Aug 9 11:14:11 dhcp6c 60699 get DHCP option server ID, len 10
Aug 9 11:14:11 dhcp6c 60699 DUID: 00:01:00:01:24:de:xx:13:xx:xx:xx:x:xx:38
Aug 9 11:14:11 dhcp6c 60699 get DHCP option client ID, len 14
Aug 9 11:14:11 dhcp6c 60699 receive reply from fe80::xxxx:xxxx:xxxx:3ab7%igb0 on igb0
Aug 9 11:14:11 dhcp6c 60699 got an expected reply, sleeping.
Aug 9 11:14:11 dhcp6c 60699 removing an event on igb0, state=RELEASE
Aug 9 11:14:11 dhcp6c 60699 script "/var/etc/dhcp6c_wan_script.sh" terminated
Aug 9 11:14:11 dhcp6c dhcp6c EXIT or RELEASE on igb0 running rc.newwanipv6
Aug 9 11:14:11 dhcp6c 60699 executes /var/etc/dhcp6c_wan_script.sh
Aug 9 11:14:11 dhcp6c 60699 status code: success
Aug 9 11:14:11 dhcp6c 60699 dhcp6c Received RELEASE
Aug 9 11:14:11 dhcp6c 60699 status code: success
Aug 9 11:14:11 dhcp6c 60699 get DHCP option status code, len 2
Aug 9 11:14:11 dhcp6c 60699 DUID: 00:03:00:01:dc:xx:xx:xx:xx:b7
Aug 9 11:14:11 dhcp6c 60699 get DHCP option server ID, len 10
Aug 9 11:14:11 dhcp6c 60699 DUID: 00:01:00:01:24:de:xx:13:xx:xx:xx:x:xx:38
Aug 9 11:14:11 dhcp6c 60699 get DHCP option client ID, len 14
Aug 9 11:14:11 dhcp6c 60699 receive reply from fe80::xxxx:xxxx:xxxx:3ab7%igb0 on igb0
Aug 9 11:14:11 dhcp6c 60699 removing an event on igb0, state=INIT
Aug 9 11:14:11 dhcp6c 60699 removing an event on igb0, state=INIT
Aug 9 11:14:11 dhcp6c 60699 reset a timer on igb0, state=INIT, timeo=0, retrans=60
Aug 9 11:14:11 dhcp6c 60699 remove a site prefix 2a02:xxxx:xxxx:80::/57
Aug 9 11:14:11 dhcp6c 60699 remove an IA: PD-0
Aug 9 11:14:11 dhcp6c 60699 send release to ff02::1:2%igb0
Aug 9 11:14:11 dhcp6c 60699 set IA_PD
Aug 9 11:14:11 dhcp6c 60699 set IA_PD prefix
Aug 9 11:14:11 dhcp6c 60699 set elapsed time (len 2)
Aug 9 11:14:11 dhcp6c 60699 set server ID (len 10)
Aug 9 11:14:11 dhcp6c 60699 set client ID (len 14)
Aug 9 11:14:11 dhcp6c 60699 a new XID (923af0) is generated
Aug 9 11:14:11 dhcp6c 60699 Sending Release
Aug 9 11:14:11 dhcp6c 60699 reset a timer on igb0, state=RELEASE, timeo=0, retrans=925
Aug 9 11:14:11 dhcp6c 60699 release an IA: PD-0
Aug 9 11:14:11 dhcp6c 60699 Start address release
Aug 9 11:14:11 dhcp6c 60699 reset a timer on igb0, state=INIT, timeo=0, retrans=278
Aug 9 11:14:11 dhcp6c 60699 remove an address 2a02:xxxx:xxxx:0:xxx:xxxx:xxxx:6938/128 on igb0
Aug 9 11:14:11 dhcp6c 60699 remove an address 2a02:xxxx:xxxx:0:xxx:xxxx:xxxx:6938
Aug 9 11:14:11 dhcp6c 60699 remove an IA: NA-0
Aug 9 11:14:11 dhcp6c 60699 send release to ff02::1:2%igb0
Aug 9 11:14:11 dhcp6c 60699 set elapsed time (len 2)
Aug 9 11:14:11 dhcp6c 60699 set identity association
Aug 9 11:14:11 dhcp6c 60699 set IA address
Aug 9 11:14:11 dhcp6c 60699 set server ID (len 10)
Aug 9 11:14:11 dhcp6c 60699 set client ID (len 14)
Aug 9 11:14:11 dhcp6c 60699 a new XID (287b01) is generated
Aug 9 11:14:11 dhcp6c 60699 Sending Release
Aug 9 11:14:11 dhcp6c 60699 reset a timer on igb0, state=RELEASE, timeo=0, retrans=938
Aug 9 11:14:11 dhcp6c 60699 release an IA: NA-0
Steve