Hi James, after trying many options, we connected to the physical AP via serial cable and manually pointed it to the Controller.

Hi Gregory,
I was wondering if you had made any progress on this? I'd trying to do almost exactly the same thing, and have come up with using

dhcp-vendorclass=cisco,Cisco

dhcp-option=cisco,43,f1:04:c0:a8:00:ca

Using dhcpdump to sniff the DHCP requests and responses looks prommising:-

---------------------------------------------------------------------------



  TIME: 2019-02-14 13:59:56.160

    IP: 0.0.0.0 (60:73:5c:2f:40:af) > 255.255.255.255 (ff:ff:ff:ff:ff:ff)

    OP: 1 (BOOTPREQUEST)

 HTYPE: 1 (Ethernet)

  HLEN: 6

  HOPS: 0

   XID: 000018b3

  SECS: 0

 FLAGS: 7f80

CIADDR: 0.0.0.0

YIADDR: 0.0.0.0

SIADDR: 0.0.0.0

GIADDR: 0.0.0.0

CHADDR: 60:73:5c:2f:40:af:00:00:00:00:00:00:00:00:00:00

 SNAME: .

 FNAME: .

OPTION:  53 (  1) DHCP message type         3 (DHCPREQUEST)

OPTION:  57 (  2) Maximum DHCP message size 1200

OPTION:  61 (  7) Client-identifier         01:60:73:5c:2f:40:af

OPTION:  54 (  4) Server identifier         192.168.0.1

OPTION:  50 (  4) Request IP address        192.168.0.249

OPTION:  12 ( 16) Host name                 AP6073.5c2f.40af

OPTION:  55 (  9) Parameter Request List      1 (Subnet mask)

					      6 (DNS server)

					     15 (Domainname)

					     44 (NetBIOS name server)

					      3 (Routers)

					      7 (Log server)

					     33 (Static route)

					    150 (???)

					     43 (Vendor specific info)

					    

OPTION:  60 ( 14) Vendor class identifier   Cisco AP c1040

---------------------------------------------------------------------------



  TIME: 2019-02-14 13:59:56.160

    IP: 192.168.0.1 (0:25:b3:25:dc:42) > 255.255.255.255 (ff:ff:ff:ff:ff:ff)

    OP: 2 (BOOTPREPLY)

 HTYPE: 1 (Ethernet)

  HLEN: 6

  HOPS: 0

   XID: 000018b3

  SECS: 0

 FLAGS: 7f80

CIADDR: 0.0.0.0

YIADDR: 192.168.0.249

SIADDR: 192.168.0.1

GIADDR: 0.0.0.0

CHADDR: 60:73:5c:2f:40:af:00:00:00:00:00:00:00:00:00:00

 SNAME: .

 FNAME: .

OPTION:  53 (  1) DHCP message type         5 (DHCPACK)

OPTION:  54 (  4) Server identifier         192.168.0.1

OPTION:  51 (  4) IP address leasetime      86400 (24h)

OPTION:  58 (  4) T1                        43200 (12h)

OPTION:  59 (  4) T2                        75600 (21h)

OPTION:  15 ( 13) Domainname                XXXXXXXXXXXXX

OPTION:  43 (  6) Vendor specific info      f104c0a800ca     ......

OPTION:   6 (  4) DNS server                192.168.0.1

OPTION:   3 (  4) Routers                   192.168.0.1

OPTION:   1 (  4) Subnet mask               255.255.255.0

---------------------------------------------------------------------------

The DHCP server seems to be passing the data I want it to, but the APs are still not finding the controller.

I'm not sure what the "option" line is doing. Does the dhcp-option need one or two IP's? I've tried googling around and not go anywhere particularly useful. You can see the dhcp-option parameter in the dnsmasq man pages. I would probably ask the Cisco people directly what they require.

From the man pages and your attempt, I'd try:

dhcp-option=enp2s0f1,vendor:Cisco AP c181543,192.168.101.210"

I can't work out if the vendor is required or not. If not specified, does it send option 43 to to every DHCP response?

Nick, thanks for your assistance. This is what I have so far:
/etc/dnsmasq.d/wifi-dhcp-option
option vendor-class-identifier "Cisco AP c1815"
dhcp-option=enp2s0f1,43,"192.168.101.210"

I've restarted the dhcp service but the AP does not appear to grab the option. Can you confirm that I have typed the lines correctly?

Hello Greg,
When setting extra options in dnsmasq, I suggest doing it in a file /etc/dnsmasq.d/any_name_you_like. You can see the format of the options in /etc/dnsmasq.d/dhcp.conf. It looks like you want something like:

dhcp-option=enpXXX,43,some_string

Where enpXXX is your LAN interface. Repeat the line for multiple LAN interfaces.
The problem is the "some_string".

From this Cisco Doc, you may just want a comma separated, quoted IP address list. Try both quoted and unquoted.

After making your change, restart dnsmasq with "service dnsmasq restart".