Joining large projects over VPN stuck on Phase 1 with error

[matjashka]

Hi, my team members report that they can't join larger projects over our (otherwise working) PPTP VPN tunnel.
After several minutes, ArchiCAD gives up with errors (as reported by users):

Server returned error code
Server connection interrupted
AND:
Unsuccessful Teamwork operation
Connection to server failed

This never happens over LAN. Our WAN outbound bandwidth for BIM server is pretty good, unless 10Mbps is considered bad. The projects start at 700MB and some are as large as 1.4GB as reported by BIM server.
Per user's ISP tech support, throttling is not the issue here. Oh, and the same user can successfully share and edit BIM projects created from scratch over the same VPN connections.

Any ideas?
We tried joining projects in the office, over LAN, and then taking them home, apparently AC16 still refuses to open the large projects.

[EDIT] I re-read the specs and noticed that my inbound firewall rule was configured for 6005 over TCP instead of UDP... I wonder if fixing that will help.

[matjashka]

OK then let me ask: where specifically do I find a human-readable Teamwork log file for ArchiCAD that will show what happened before the teamwork failed?
The logs I see in ~/Library/Logs/Graphisoft/ are in binary format.

[David Shorter]

Could be that ArchiCAD is timing out and is becoming impatient with a slow connection.
Perhaps there is a setting which can be changed to allow for a slower connection speed.

[matjashka]

Both server and client have high speed internet (symmetrical T1 server side).
Slower connections were tested and worked.

After various tests I suspect undisclosed traffic throttling activities from an exotic ISP. They have to make their money somewhere and peer-to-peer computing just takes bandwidth. But that's just my theory.

If I learn what *actually* happens, I'll post.

[matjashka]

OK, because I was receiving PM from people who encounter similar problems, let me describe the troubleshooting we did.

Conclusion so far: ISP throttling peer-to-peer traffic
Why: It works and then stops working on what appears to be a monthly cycle

Troubleshooting:
Server-side firewall rules -- checked (just in case) if required ports ports are open both ways. Made sure that ports required for VPN were open PLUS the ports required for specific services were open (and not translated to any specific network address, because this is only for PPTP which will assign you an local IP).

Client firewall rules -- unlikely, but some older modems/routers come with rules that block VPN traffic.

PPTP log -- asked coworker to send me his PPP log file and saw the persistent errors that indicated lots of dropped packages, either because of bad network, or slow speed, or bad encryption, or wrong package size or... something not letting the packages go through.

ISP throttling peer-to-peer traffic? -- his ISP said "no". But ISPs can filter out peer-to-peer traffic and throttle it while downloading movies from the big guys still works. The client ISP bumped up his speeds to 50mbps to troubleshoot the issue, but it didn't help.

Different ISP -- Teamwork over VPN worked over a different ISP without problems, at least initially, which confirmed that our configuration was OK.

Small files vs big files -- tested if big files can be transferred using ways other than Teamwork (over SSH or VPN). They could not, in our case, while at the same time coworker could create new Teamwork projects from scratch over the same connection.

Data packages too big, causing timeouts? -- Tested a number of different MTU size settings on our router and on client hardware, safe default is between 1400-1500 but there are many custom settings flying around. The Ping tool can be tested with various package sizes, and you can ask your coworker to ping back to your server/router to see what is the MTU limit. But everything seemed OK.

At this point I gave up and blamed coworker's ISP.

2-3 weeks later, that same coworker came back to report that Teamwork WAS working over VPN, no config changes on our side. 2-3 weeks later he came back again to report that Teamwork WASN'T working again.

So, I still blame his ISP. YMMV.