Error Codes - 6023 and 6024 (Unable To Negotiate A Successful Connection)

If you're using a Paperspace machine, we are now dynamically assigning IP addresses to the machine to overcome this issue. This can take a few minutes based on Paperspace's system. If it happens when you're trying to connect to that Paperspace server, give it a couple minutes and try again. It should work. If it doesn't, please fill out this form for support - thanks.

Parsec makes a peer-to-peer connection between two computers. For that to work, we need to find a way to connect the two computers. When one of those two computers is blocked by a double/symmetric NAT, we can make the connection anyway. When both computers are blocked, you will receive this error.

Are you the host? Go to HOST SOLUTION

Are you the client? Go to CLIENT SOLUTION

Are you connecting to a cloud machine? Go to CLOUD SOLUTION

HOST SOLUTION

Step 1.  Do all your friends get the 6023 error?

  • Yes, everyone gets 6023 errors (go to step 2) 
  • No, some can can connect but others can't (go to step 3)

Step 2. Do this if you can forward ports or turn UPnP on in your router.

  • Make sure your router has static DHCP leases turned on.
  • First try turning UPnP on and have a friend try connecting to this hosting computer.
  • You should forward ports 8000 - 8002 UDP on your router, and add 8000 as your start port for the host to the Parsec Network Settings. You should increase the range from 8000 - 8011 if you have 4 friends connecting at the same time.
  • Make sure you allowed Parsec through your Windows Firewall.
  • Reboot your router and computer.

Step 3. The host doesn't have access to its router config settings. 

  • Ask friends to make sure their router has static DHCP leases turned on.
  • Have your friend try turning UPnP on and have a friend try connecting to this hosting computer.
  • You should tell your friends who can't connect to forward ports 9000 - 9002 UDP on their router, and add 9000 as their start port for the client to the Parsec Network Settings
  • If they can't do port forwarding because they're not allowed, you may need to use a P2P VPN solution like ZeroTier.  
  • Make sure they allowed Parsec through their Windows Firewall.

CLIENT SOLUTION

Step 1.  Have you ever been able to connect to anyone via Parsec using this internet connection?

  • Yes, but when connecting to a specific friend I get a 6023 (go to step 2) 
  • No, this internet connection has never worked (go to step 3)

Step 2. 

  • Ask your friend to try turning UPnP on in his router and confirming that you have a static DHCP lease.
  • You should ask your friend to forward ports 8000 - 8002 UDP on their router, and add 8000 as their start port for the host to the Parsec Network Settings
  • Make sure they allowed Parsec through their Windows Firewall.

Step 3.  

  • You should see if you can turn UPnP on in your router and confirm that you have a static DHCP lease.
  • You should forward ports 9000 - 9002 UDP on your router, and add 9000 as your start port for the client to the Parsec Network Settings
  • If you can't do forwarding because you're not allowed, you may need to use a P2P VPN solution like ZeroTier.
  • Make sure you allowed Parsec through your Windows Firewall.
  • Reboot your router and computer

CLOUD SOLUTION

Step 1.  Have you ever been able to connect to a cloud machine using this internet connection?

  • Yes, it has recently stopped working (go to step 2) 
  • No, this internet connection has never allowed me to connect to my cloud machine (go to step 3)

Step 2. 

  • Has something changed with your internet connection? (Think internet plan, computer firewall, anti-virus, router settings). 
  • What about if you reboot your router? 
  • What about if you reinstall Parsec? 
  • Did you change from AWS to Paperspace cloud machine?  If you did, follow step 3 below. 

Step 3.  

  • You should forward ports 9000 - 9002 UDP on your router, and add 9000 as your start port for the client to the Parsec Network Settings
  • If this doesn't help, you simply may be unable to access one of our cloud providers Paperspace, and you may need to switch to AWS. 
  • Make sure you allowed Parsec through your Windows Firewall.

 

If none of this helps please create a support ticket here

 

MORE INFORMATION - WHAT'S HAPPENING BEHIND THE SCENES BEFORE I GET THIS ERROR?

Parsec uses several techniques to try to connect two machines with peer-to-peer UDP. First, we look to see that you have port forwarding manually enabled. Parsec attempts several methods for connecting two computers. The last resort is a negotiated connection. The chart below gives a high level diagram of this type of connection.

Artboard.png

Essentially, we have a server that listens to both machines. Finds out which ports are open via hole punching. Once the hole punch occurs, our server tells the two machines how to they can talk to each other, and a direct peer-to-peer connection is made. Other P2P services are able to use a fourth method for connecting two machines. They basically relay a message through a central server. This works for other services that don't worry about lag. Of course, since we're 100% focused on lowering latency, this isn't possible for us. That's why Skype might work for you, but Parsec might not.

WHY CAN'T I MAKE A CONNECTION?

If you're getting error 6023, it's because something is getting in the way of the hole punching or your firewall needs an exception for Parsec for both private and public connections. Some ISPs have been blocking the UDP connections. More likely, however, you probably have a Double NAT. Double NATs are a situation where you have multiple network devices on the same private network. This happens a lot when your ISP gives you a modem and a network device for Wifi. This article (also linked above) gives some thoughtful ways to resolve a Double NAT. It's nearly impossible for us to penetrate a Double NAT. We recommend trying to manage this via manual port forwarding, which will require port forwarding from the modem to your network switch and then from the network switch to your PC. Unfortunately, we're doing everything we can automatically for Double NATs. If the issue persists for you, please try to resolve manually.

PFSENSE OR OPNSENSE

PfSense is a great program for firewall management, but there's a required workaround to get past the 6023 error with this software. If you're trying to connect, but you use pfSense or OPNsense at home as your gateway/firewall, you might need to set Hybrid NAT rules, with a rule pointing to your local IP (having a static DHCP lease helps here).