Changes as of 2024.06.03.02 The “_useipv6.txt” and “_usesteam.txt” files have been moved to the Member’s AppCache directory (%LOCALAPPDATA%\<dir>).

All race farms now support both IPv4 and IPv6.

You can tell iRacing to use IPv6 for your connections to race servers by opening the iRacingUI, clicking the Settings icon at the bottom right, and moving the IPv6 switch to on.  If that switch won't respond, or just keeps moving back to off, then you do not have IPv6.  You can check if you have IPv6 by clicking here:

If you've confirmed that you have an IPv6 address with the link above but still cannot enable it in the iRacing UI, then it's likely that the iRacing service started up before Windows established its IPv6 addressing.

You can tell the iRacingService to wait to start until more of the Windows networking is configured by creating a new text file and naming it core.ini, including the following section, or by downloading the file attached to this FAQ.


dependOnLanManWorkstation=1 ; Should the iRacingService depend on LanManWorkstation?

You must put this new core.ini file in the folder where iRacing is installed (default install location is C:\Program Files (x86)\iRacing). This is not the core.ini in the Documents/iRacing folder.

After adding the lines above to your core.ini file in your iRacing installation directory, reboot your computer and try enabling IPv6 in the iRacingUI.

You can also fix the problem temporarily until the next reboot by double-clicking the Start_iRacingService.bat script in the iRacing installation directory.

For most customers, there will be little noticeable difference between running with IPv6 and IPv4 (the default). However, for some, the IPv6 routing from their ISPs is significantly worse than IPv4, and for others, it will be significantly better.

You can see your IPv4 and IPv6 ping times while on the classic member website by hovering your mouse cursor over the "Ping" note at the top of the site. In the iRacing UI, you can click the "connections" icon on the top bar and hover your mouse cursor over the bar graphs next to each farm/protocol. Look at the "Average Ping" value.

If you should find that IPv6 is better for some of our server farms but IPv4 is better for others, there is a way you can handle this.  You can enable the simulation to use IPv6 as described above.  Then, in your My Documents\iRacing directory, you can (while the simulation is not running) edit a file named "app.ini".  You can double-click on this file, and edit it using Notepad.  Add the "excludeIPv6OnFarms=" setting to the [Misc] section.

excludeIPv6OnFarms= ; Comma-separated list of 0 or more of farms to not race using IPv6: (bosrace,sydrace,amstrace)

On the right side of the =, list the farms you do NOT want to use IPv6.  For example, if you find that your ping times to our Amsterdam and Boston farms are better with IPv4 but are better to Sydney with IPv6, you can tell us not to use IPv6 to our Amsterdam or Boston farms.

excludeIPv6OnFarms=amstrace,bosrace ; Comma-separated list of 0 or more of farms to not race using IPv6: (bosrace,sydrace,amstrace)

You can also shorten those entries down to just "ams", "bos", and "syd".

As of 2019/07/30

In the "IPv6 is worse than IPv4" camp, there are:

  • Charter cable subscribers in the northeast US have worse ping times to our Boston race farm than IPv4.
  • A fair number of users in Australia have higher pings to our Boston farm than they do with IPv4, but that will most likely be resolved with our new AU/NZ circuit.
  • A fair number of users in Brazil have worse IPv6 ping times than our Boston farm. Some ISPs there route IPv6 only through China Mobile, with traffic going to the US West Coast instead of to Miami.

The IPv6 will be better than the IPv4 camp:

  • Some iRacing customers are using ISPs that have something called "Carrier Grade NAT" (CGN), and some of those ISPs seem to have poorly implemented this technology. We sometimes see cases where a customer's ISP changes their IPv4 address out from under them in the middle of a race. This causes a disconnection from the race. We have mostly seen this from small ISPs here in the US, but originally started noticing this behavior from ISPs in Germany. For these users, you definitely should switch to IPv6.