Comcast IPv6 broke ARD

For many years i have been helping a gentleman, now in his mid-80s, with his Mac. Up until a couple of months ago, he would give me his then-current public IP address over the phone, and i’d have no trouble getting Apple Remote Desktop 3.4 running on any of several Tiger Macs here to connect to his PowerMac3,1 (Power Mac G4 AGP single processor 400 MHz) to help him. Worked great.

His ISP is Comcast, in Portland, Oregon (many hundreds of miles away from me in southern California). Comcast recently changed to IPv6 in his area (and i can’t blame them… it’s 2015). I can no longer connect to his Power Mac no matter what i do. Here’s some more information:

* I have the correct IPv6 address for his Mac (visible in the raw source of his Mail email messages to me), so no error there.

* I have used Macs running 10.5, 10.6, and 10.9 using Screen Sharing and both unbracketed and bracketed versions of his IPv6 number: can’t connect.

* The home router here is an Apple Time Capsule, new in January 2012.

* Our ISP is Charter, running IPv4.

* Tried Chicken (newer) and Chicken of the VNC (older): neither one worked, though Chicken was closer (same basic error as Screen Sharing with the newer OSes. In the case of Chicken, this error was: “Could not connect: no route to host”).

My sense is that the ARD client (server? the part that comes with the OS) version 3.4 on his PowerMac3,1 can’t work with IPv6, but of course trying to get this sort of information is extremely difficult (does anyone know for sure?). I do know that my ARD admin 3.4 does not work with IPv6, and that IPv6 support wasn’t added until something like ARD admin 3.7, which is why i’ve been using Screen Sharing (or as i think of it, ARD admin lite) on the newer systems here at my end.

I happen to have a close-enough Mac to his: Power Mac G4 (Gigabit Ethernet). To try and eliminate as many variables as possible, i set up a machine-to-machine direct Ethernet connection, shut off IPv4, and tried to connect via IPv6. Here are the specifics:

Test setup:

1) Connect the two Macs (PPC G4, one running OS 10.5.8 and the other OS 10.4.11) via Ethernet. Disable AirPort/other networking.

2) Ensure System Preferences > Sharing > Apple Remote Desktop is enabled on the remote Mac (a 10.4 system. The name changes to Screen Sharing for 10.5 and newer).

3) Disable IPv4 (Configure IPv4: Off) on both machines, under Ethernet.

4) Ensure IPv6 for Ethernet is working, set to Automatic.

The 10.4 machine has an IPv6 fe80 address, with no router address.

The 10.5 machine shows no IPv6 address nor router address nor prefix length. Restarted it: same condition.

5a) Open a Finder window. Locate the remote Mac under Shared, click it.

6a) In the window which opens, click Share Screen….

The Screen Sharing app runs. Screen sharing/remote machine control works as expected.

5b) In Finder, Go > Connect to Server…

6b) Enter the IPv6 address:

vnc://[fe80: (etc. etc.)]

7b) Click Connect.

Expected result: same as end of step 6a above: It should be possible to see and control the remote Mac.

Actual result: Screen Sharing app runs, with the error:

Connection failed to “fe80:0000:0000:0000:0230:65ff:fed5:5fa8”.

Please make sure that Screen Sharing (in the Sharing section of System Preferences) is enabled on the computer to which you are attempting to connect. Also make sure your network connection is working properly.

Is this evidence that 10.4 systems cannot connect via IPv6? Did i make a mistake? If i did, how can i better locally test an IPv6 numerical connection?

The problem is that the gentleman i am helping is suffering more and more every day from dementia. He very much does not want to upgrade his Mac (nor can he do it on his own), and i can’t get him to use his wife’s iPad (zero monetary outlay). He is no longer able to update TenFourFox on his own, and since the Comcast IPv6 change, i can no longer connect to him to do it for him, no matter what i try here at my end.

Anyone have any thoughts/suggestions on getting this working again?

Anyone live in Portland, Oregon willing to help a kind elderly gentleman stay online securely, in my stead?

Thanks!