This error means something is preventing Parsec from making a peer-to-peer network connection between you and the other computer. This could be prevented because of NAT issues, firewall issues, improper/non-existent port forwarding, or even if your ISP has been blocking the UDP connections.
To resolve this, make sure to check everything below on both of the computers that are trying to make the connection. That makes it more likely for the issue to be resolved.
Restart the computer and router
Sometimes, simply restarting everything fixes this error. Restart the computer and router on both the host and client computer which are having issues.
Allow Parsec on the firewall
Both the host and client should make sure that Parsec is allowed on the firewall. Here's how to do it on Windows:
- Press Windows key + R, paste control firewall.cpl and press Enter
- Select "Allow an app or feature...." in the sidebar
- Click Change settings, search for Parsec and enable the checkboxes, then click OK
If you want to be absolutely sure your firewall isn't the culprit, you can also disable it temporarily by going to "Turn Windows Defender on or off" in the sidebar instead of "Allow an app or feature....". In this section, temporarily disable everything, and attempt to connect Make sure to re-enable once you find out that's not it, though, or your PC will be more vulnerable to security issues.
Make sure your home isn't using two routers
If, for example, you purchased your own router and plugged it directly into your internet provider's router to improve the Wi-Fi signal in your house, that can prevent Parsec from making the connection.
If the host or client's home has multiple routers, make sure to connect your device directly to the router that provides internet, most likely the router given by your internet provider that plugs into the wall outlet (either cable, fibre, or DSL). If you cannot do that, you can alternatively search online how to change the other router's settings into something called either access point or bridge mode.
Check if your network is too restrictive (carrier-grade NAT)
One of the main issues that can prevent a connection from happening is when your internet provider uses a "carrier-grade NAT" in their infrastructure. If both sides trying to make a connection have this issue, then Parsec cannot make the connection happen.
How do I check I have this issue?
Make sure to check for this on both sides (both computers involved in the connection). The steps for Windows are as follows:
- Press Windows key + R
- Paste this onto the new window:
cmd /k tracert 18.104.22.168
- Press Enter. A new black window will show up
- Wait for a while until it shows 'Trace complete.' You'll see a list of IPs in the window
Check if any of the IPs in the black window (except the first IP) are in this list:
- 192.168.0.0 to 192.168.255.255
- 10.0.0.0 to 10.255.255.255
- 172.16.0.0 to 172.31.255.255
- 100.64.0.0 to 100.127.255.255
If you see any that are in the list, that is bad news, you're likely behind a carrier-grade NAT. The exception is if the IP you saw has the exact first 3 sets of numbers as the first IP in your black window, which means it can be safely ignored (for example, 192.168.0.1 at the start of the list, followed by 192.168.0.10 is ok).
How can I solve this?
- If both sides have the issue: Either side can request to get a dynamic or static "public IP" from their internet provider. It's often free or inexpensive to get, and if you want to use Parsec often, it's the way to go. With only one person behind a carrier-grade NAT, Parsec should be able to make the connection just fine.
- If only one side has the issue: The side that does not have the issue can try to configure their router, which might be all that is needed to get your network open enough for Parsec to work. To learn how to configure the router, read further below.
Configure your router
If you ensured you don't have any of the issues listed beforehand, you can try configuring your router below. If you're behind a carrier-grade NAT, configuring the router will not fix your issue. You might however be able to configure the router on the opposite machine, if it does not also have a carrier-grade NAT.
Solutions for people using pfSense or OPNsense
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).
Nothing fixed it, what do I do?
Make sure that you have not skipped any of the sections above, especially the one on carrier-grade NAT and configuring your router. Unfortunately networking is complicated, and although Parsec has a few tricks on its sleeve (like UDP hole punching, which can allow situations where only one of the computers have to be sufficiently open), it cannot always make the connection happen without configuration from you as the user.
If you are a Parsec for Teams customer, keep in mind there may be additional things of note about how your team has set up Parsec, and if you are stuck you may want to contact the Teams-specific support by opening your Parsec app, and clicking the Help icon.
If everything else in this article has been looked into but did not help, but you want to try another solution at the cost of possibly worsening the latency of the stream, you can follow this tutorial on using the ZeroTier P2P VPN. This is not a guaranteed fix, and you may have issues with it even if it works, but it's the only option left if everything else has failed to resolve the error.