AirPort Extreme and minimal upload speed challenges

[wlwesq]

Good day, all --

I'm not having the closed port issue that seems to befuddle many here, but it's somewhat similar. I've read the forums quite a bit, used the help feature in Transmission, and been through the Transmission wiki (very handy!). Still, I'm stuck.

Basically, I'm using an AirPort Extreme Base Station with Comcast as the broadband provider. I'm running Transmission to share torrented files.The torrents are pretty active with a good number of peers. Downloading is no problem at all--I get great download speeds. Uploading is the problem.

I have Transmission set to randomize the port upon opening and to automatically port forward. What happens is that the upload speed will be 0 for the most part, every few seconds it will show 8.0 KB/s, maybe 16.0 KB/s, once in a while 24.0 KB/s.

If I have the preferences open to the network settings, I can click the randomize button. Initially it will be red, but then usually after it does a bit more chewing on the thing, it goes green. But the upload speeds remain the same usually.

If I repeatedly click randomize over the course of several minutes, I will once in a while get a port that is both open and with significantly improved (100 KB/s or more) upload speeds. Unfortunately, it lasts for maybe 30 minutes and then dies off again. Clearly not a "set it and leave it" situation.

I have my OS X firewall turned off since I believe I'm behind the AEBS firewall. I've tried monkeying with various settings on the AEBS but nothing seems to be cooperating. Here are the current settings:

Transmission
Bandwidth limits both off
Peers 200, 60 for new transfers
Peer exchange PEX is on
Distributed hash table DHT is on
Prefer encrypted peers is on
Ignore unencrypted peers is off
Peer listening port is open
Randomize port on launch is on
Automatically map port is on

AirPort Extreme Base Station
Config IPv3 set to Using DHCP
Connection Sharing: Share a public IP address
DHCP beginning address 10.0.1.201
Ending address 10.0.1.254
DHCP Lease 1 day
NAT enable default host is off
NAT enable NAT Port Mapping Protocol is on
In Port Mapping, I have allowed bit torrents access (Advanced > Port Mapping)
The specs there are: Public UDP Ports 40000-70000
Public TCP Ports 40000-70000
Private IP address 10.0.1.201
Private UDP Ports 40000-70000
Private TCP Ports 40000-70000

(I know those 40K to 70K range is probably overkill, but what the heck.)

Any thoughts or suggestions? I know Comcast likes to prohibit seeding when possible, but they're really the only broadband option at this point.

Many thanks in advance!

[cheule]

It's possible that even with your very good attempt at allowing port mapping through (the huge range you set), that something is awry. I suggest you place the computer you are doing the transmission on, inside the DMZ which with Apple's products is called "default host." (under manual setup, Internet, NAT, default host) This makes all ports open to that NAT endpoint. In such a case, I would make sure your computer isn't running unnecessary services, that passwords are enabled on any services you run.

Also another possibility is that you have a double NAT situation. That would mean that your comcast "modem" is using NAT, and then your Airport has created a subnet below that. If that's the case, you need to put your comcast modem into bridge mode, or at the very least place the Airport address inside the DMZ for the comcast modem (doing that isn't a good idea, as you increase network overhead, bridge mode is a far better solution).

[wlwesq]

Thanks--I'll have to look into those ideas.