Messages/(AIM) Screensharing failing to initiate on Yosemite 10.10.4

I'm hoping the illustrious sees this, because I'm not sure there's any other way we will ever find a resolution.

For nigh unto a decade I have used AIM screensharing (originally through the iChat app and now through Messages) to share & control screens remotely with colleagues. For the last few months it has been broken, and no sharing can be initiated in either direction. Web searches for error codes and messages yields nothing. iChat screen sharing is an extremely powerful tool for the way we work, putting many of the alternatives (skype, join.me, etc) to shame in its ease of use and availability for those running a Mac. It's also infuriatingly prone to hiccups, bugs, and problems, as anyone that's used it for as long as we have can attest. I consider that a testament to its goodness, as much as to its badness. 😉

If you're seeing this, Ralph, we are extremely keen to hear your thoughts on how we can begin troubleshooting. Below is a dump from the report that is sent to Apple every time we try (and fail). Thanks!

P.S. We have so far troubleshooted by doing the following:

- Dump the com.apple.iChat.AIM.plist

- Repair permissions (note this message is returned: "Warning: SUID file “System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/MacOS/ARDAg ent” has been modified and will not be repaired."

- Turn Sharing on in System Prefs (I now understand this controls the APPLE/MESSAGES screensharing utility, but does not affect the AIM/JABBER side)

- Restarting Messages, rebooting, etc.

- Specifying ports on the Apple Time Capsule routers

- Attempted screensharing with other colleagues/parties with no luck

- Checked connection doctors, modified bandwidth limitations every way to sunday

==========================================================

Date/Time: 2015-08-03 12:09:30 -0600

OS Version: 10.10.4 (Build 14E46)

Report Version: 4

Messages Connection Log:

2015-08-03 12:08:53 -0600: 0x610000388540: State change from No State to Invited.

2015-08-03 12:09:06 -0600: 0x610000388540: State change from Invited to Connecting.

2015-08-03 12:09:26 -0600: 0x610000388540: State change from Connecting to Ended.

2015-08-03 12:09:26 -0600: 0x610000388540: Error -1 (An unknown error occurred.)

Video Conference Error Report:

38.018746 @/SourceCache/VideoConference/VideoConference-473/SIP/SIP.c:2255 type=4 (900A0015/0)

[SIPConnectIPPort failed]

[]

Video Conference Support Report:

22.036561 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:1973 type=2 (00000000/0)

[Connection Data for call id: 1 returns 1

]

[]

29.995287 @/SourceCache/VideoConference/VideoConference-473/VCChannel/VCChannel.m:303 type=2 (00000000/0)

[VCChannel prepareConnectionWithRemoteConnectionData - remote VCConnectionData: 1]

[]

30.011261 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:1988 type=2 (00000000/0)

[Prepare Connection With Remote Data - remote VCConnectionData: 1, local VCConnectionData: 1

]

[]

30.012953 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:2180 type=2 (00000000/0)

[Initiate Conference To User: u0 with Remote VCConnectionData: 1 with Local Connection Data: 1 conferenceSettings: 1]

[]

36.015314 @/SourceCache/VideoConference/VideoConference-473/SIP/Transport.c:2144 type=1 (00000000/0)

[INVITE sip:user@rip:16402 SIP/2.0

Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK0654460d5fd0b955

Max-Forwards: 70

To: "u0" <sip:user@rip:16402>

From: "0" <sip:user@lip:16402>;tag=1764735184

Call-ID: 1e53a0abecbe492-3a0a-11e5-a957-cf73694a4012@lip

CSeq: 1 INVITE

Contact: <sip:user@lip:16402>;isfocus

User-Agent: Viceroy 1.4

Content-Type: application/sdp

Content-Length: 345

v=0

o=xxxxxxxx 0 0 IN IP4 lip

s=0

c=IN IP4 lip

b=AS:2147483647

t=0 0

a=hwi:1028:4:2600

a=iChatEncryption:NO

a=bandwidthDetection:YES

m=audio 16402 RTP/AVP 110 12 124 3 0

a=rtcp:16402

a=rtpmap:110 X-AAC_LD/22050

a=rtpmap:3 GSM/8000

a=rtpmap:0 PCMU/8000

a=rtpmap:124 iLBC/8000

a=fmtp:124 mode=30

a=rtpID:3431477822

]

[]

36.518126 @/SourceCache/VideoConference/VideoConference-473/SIP/Transport.c:2144 type=1 (00000000/0)

[INVITE sip:user@rip:16402 SIP/2.0

Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK0654460d5fd0b955

Max-Forwards: 70

To: "u0" <sip:user@rip:16402>

From: "0" <sip:user@lip:16402>;tag=1764735184

Call-ID: 1e53a0abecbe492-3a0a-11e5-a957-cf73694a4012@lip

CSeq: 1 INVITE

Contact: <sip:user@lip:16402>;isfocus

User-Agent: Viceroy 1.4

Content-Type: application/sdp

Content-Length: 345

v=0

o=xxxxxxxx 0 0 IN IP4 lip

s=0

c=IN IP4 lip

b=AS:2147483647

t=0 0

a=hwi:1028:4:2600

a=iChatEncryption:NO

a=bandwidthDetection:YES

m=audio 16402 RTP/AVP 110 12 124 3 0

a=rtcp:16402

a=rtpmap:110 X-AAC_LD/22050

a=rtpmap:3 GSM/8000

a=rtpmap:0 PCMU/8000

a=rtpmap:124 iLBC/8000

a=fmtp:124 mode=30

a=rtpID:3431477822

]

[]

37.519444 @/SourceCache/VideoConference/VideoConference-473/SIP/Transport.c:2144 type=1 (00000000/0)

[INVITE sip:user@rip:16402 SIP/2.0

Via: SIP/2.0/UDP lip:16402;branch=z9hG4bK0654460d5fd0b955

Max-Forwards: 70

To: "u0" <sip:user@rip:16402>

From: "0" <sip:user@lip:16402>;tag=1764735184

Call-ID: 1e53a0abecbe492-3a0a-11e5-a957-cf73694a4012@lip

CSeq: 1 INVITE

Contact: <sip:user@lip:16402>;isfocus

User-Agent: Viceroy 1.4

Content-Type: application/sdp

Content-Length: 345

v=0

o=xxxxxxxx 0 0 IN IP4 lip

s=0

c=IN IP4 lip

b=AS:2147483647

t=0 0

a=hwi:1028:4:2600

a=iChatEncryption:NO

a=bandwidthDetection:YES

m=audio 16402 RTP/AVP 110 12 124 3 0

a=rtcp:16402

a=rtpmap:110 X-AAC_LD/22050

a=rtpmap:3 GSM/8000

a=rtpmap:0 PCMU/8000

a=rtpmap:124 iLBC/8000

a=fmtp:124 mode=30

a=rtpID:3431477822

]

[]

44.091900 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:1973 type=2 (00000000/0)

[Connection Data for call id: 3 returns 1

]

[]

49.936581 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:1988 type=2 (00000000/0)

[Prepare Connection With Remote Data - remote VCConnectionData: 1, local VCConnectionData: 1

]

[]

49.936859 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:2180 type=2 (00000000/0)

[Initiate Conference To User: u0 with Remote VCConnectionData: 1 with Local Connection Data: 1 conferenceSettings: 1]

[]

Video Conference User Report:

0.000000 @:0 type=5 (00000000/16402)

[Local SIP port]

[]

30.011386 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:2085 type=5 (00000000/0)

[Remote Router]

[FULLCONE]

30.011390 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:2087 type=5 (00000000/0)

[Remote CommNAT Result: 0x00000102

]

[]

30.012956 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VideoConferenceGlobalObjects.m:1679 type=5 (00000000/0)

[Router]

[FULLCONE]

30.012959 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VideoConferenceGlobalObjects.m:1681 type=5 (00000000/0)

[CommNAT Result: 0x00000102

]

[]

49.936720 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:2085 type=5 (00000000/0)

[Remote Router]

[FULLCONE]

49.936727 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VCInitiateConference.m:2087 type=5 (00000000/0)

[Remote CommNAT Result: 0x00000102

]

[]

49.936863 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VideoConferenceGlobalObjects.m:1679 type=5 (00000000/0)

[Router]

[FULLCONE]

49.936867 @/SourceCache/VideoConference/VideoConference-473/Video Conference/VideoConferenceGlobalObjects.m:1681 type=5 (00000000/0)

[CommNAT Result: 0x00000102

]

[]