One computer.
If itâs an FTDI driver stack/interaction problem as expected, FWIW another potential workaround for desktop PC users is to install a 1-port PCIe serial adapter card (e.g., StarTech PEX1S953LP is ~$40 - same price as PerfPro bridge).
Advantages: You donât need to buy 2x ANT+ adapters (~$30), worry about driver/stack maintenance/support issues with PerfPro SW stack and/or ANT+ adapter drivers, or introduce an unneeded wireless link.
Disadvantages: It will ONLY work with PC apps, and not with other wireless devices that support ANT+ FE-C. Obviously, you need a desktop PC with a spare PCIe slot.
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Any ideas this workaround will work with a Macbook?
Not sure. Most of my friends use a PC. The software has a 14 day free trial.
This sounds interesting for one CompuTrainer. I have four CompuTrainers connected to my computer with up to four family members riding simultaneously at once, each with their own Zwift window. Four at once is rare, but three at once is somewhat common. Any idea if I would need 6 or 8 ANT+ dongles for this situation? If so, it probably wonât work due to insufficient USB ports, and, even with a USB hub to add ports, I suspect the computer would run out of addressable resources.
This sounds like an interesting idea for those using a desktop PC with Zwift like me. Have you or anyone confirmed whether it resolves the current pairing issue? Iâm inclined to try it, even if just to avoid the hassle of future automatic incompatible FTDI driver updates. Iâll have to check if I still have the old CT stereo-to-DB9 serial cables.
Perhaps the following information could help Zwift technical support narrow down the problem. I found two old stereo-to-serial adapters that came with my older CompuTrainer years ago. CT stopped supporting them at some point pre-Zwift days and switched to the FTDI stereo-to-USB adapters I have been using since. I thought to myself, letâs see if Zwift can pair to my CT with this!
So I plugged in my CT through one of the old adapters (see photo), and it appeared in Device Manager as âProlific USB-to-Serial Comm Portâ with a Prolific driver from 2010 assigned to COM7. First I launched RacerMate One out of curiosity, but as expected it did not recognize anything on COM7. Then I launched Zwift. To my surprise, Zwift saw my CompuTrainer on COM7 and paired with it! But then 2 seconds later it dropped the pairing. When I unplugged the USB adapter and plugged it back in again, it reappeared and I could pair with it again, but then it would drop it again after 2 seconds. So, very similar behavior with the FTDI adapters.
This suggests the CT pairing problem has nothing to do with FTDI drivers or anything specific to the FTDI adapter, but rather simply how Zwift is handling COM port communication in general starting with version 1.105.
I then ran Windows Update, and it updated the Prolific driver to one dated 2024 and Device Manager displayed it as âPL2303HXA PHASED OUT SINCE 2012. PLEASE CONTACT YOUR SUPPLIERâ, and it was still assigned to COM7. I rebooted my PC to be certain it would use the new driver, and then Zwift could no longer find COM7. So I am guessing the 2024 driver is a dummy driver that just disables the adapter. When I rolled back the driver to the 2010 version, Zwift was able to pair with the CT again on COM7 but as before only for 2 seconds.
Add me to the list of Computrainer owners with the problem that my CT shows up for seconds and disappears. I canât give you a date of onset bc I have been sick for several weeks, but it is a new problem since I came back. I am using the workaround above to hit OK quickly, which I can also do if I am in ride and unplug/replug and then pair (which I do to recalibrate after riding a while). However, I hope that Zwift can fix this issue in a more satifactory way soon.
Man, Zwift is really trying hard to avoid the blame for this. Today I received a very confident Zwift support response to my support request, and the response even mentioned my previous post in this thread about my testing with the Prolific adapter, telling me the problem is the FTDI driver and that I need to roll it back to version 2.12.36.4. I was like, yeah, thanks, we figured that one out like 3 months ago⌠and my testing of the Prolific adapter that you mentioned makes it clear it has nothing to do with the FTDI driver!! A clear minded read of this thread shows that the FTDI driver is not the problem, as we are all using driver version 2.12.36.4 - otherwise we would not even be able to pair the Computrainer for the measly 2 seconds that we are!
Anyway, I have some new information that corroborates what I found using the Prolific serial-to-USB adapter. I purchased and installed a PCIe expansion card that provides up to four DB9/RS232 old-school serial ports. I connected the old stereo-to-DB9 serial adapter that shipped with my older Computrainer directly into one of the serial ports now on the back of my computer, thanks to the PCIe expansion card.
And the behavior is the same. Zwift sees the Computrainer, pairs with it, then drops the pairing 2 seconds later. Same as with the FTDI stereo-to-USB adapter, and same as with the Prolific serial-to-USB adapter.
Then I remembered seeing a little while back a Zwift posting about a new pairing screen, and realized that I wasnât seeing any new features on my pairing screen. So I pulled up the Zwift post by Shuji: Updated Pairing Screen UI [January 2026] - Whatâs New? / Zwift Game - Zwift Forums
According to the post, I should be seeing a âconnection type iconâ next to the trainer name (and next to other paired devices), and a âsensor relay becon (sic)â. I donât see either for the few seconds my Computrainer is paired, not when using the FTDI adapter, nor when connecting directly via serial port, and I also donât remember seeing that when I paired with the Prolific adapter. But here comes the kicker from that post - âThe (connection type) icons for each signal show how theyâre paired: WiFi, Ethernet, Bluetooth, ANT+â. Did you notice whatâs missing? No option for serial ports! This seems to confirm what I have been suspecting and what my testing with different methods of connecting the Computrainer seems to show. Zwift is not supporting serial / COM port connections anymore. The post says the new pairing screen features are âenabledâ in version 1.106, but I will bet some of the code was already in version 1.105 and that is what has screwed up our ability to pair our Computrainers, or probably any type of trainer that uses a serial port (if there are any others).
So they rolled out these cute little icons to help their poor users troubleshoot their frequently dropping wireless connections, but in the process completely ignored and screwed up the original reliable hard-wired serial port connections that Computrainers use!
Zwift - if I am right, could you not just simply release a version of Zwift that removes the code for the new pairing screen so us Computrainer users can ride again? You can roll it out again in a future version after you figure out how to include serial ports and not break serial port pairing. Letâs be real, the connection icons are nice, but they donât provide any new functionality - and they actually completely remove all functionality for Computrainer users. Assuming I am right, of course.
Attached are images of my serial port connection for my Computrainer, and screenshots of two Zwift pairing screens, one using the FTDI adapter, and one using the direct serial connection (taken during the 2 seconds before the pairing dropped).
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I added a post to the Updated Pairing Screen UI [January 2026] thread with a theory on how the new pairing screen features might be causing Zwift to drop pairing with Computrainers.
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Thanks, Michael, for your research and advocacy. I see that aliexpress has cheap serial-to-Ethernet cables (search âCat5 Ethernet To Rs232 DB9 COM Port Serial Femaleâ). With this cable, do you think Zwift would recognize a CT as connected via Ethernet or would it still appear as a COM port connection?
Mark, I donât know enough to answer your question. My guess is that adapter will just transmit the serial signal over the Ethernet plug, and thus it will still be a serial signal that Zwift is not supporting right now. You would probably need a powered adapter with a chip to convert the signal to an Ethernet signal.
Now, maybe whatever trainers that are using Ethernet are transmitting a serial signal, but I doubt it for two reasons. The first is, again, my testing shows Zwift does not support serial input since version 1.105. And secondly, I suspect the trainers using Ethernet are offering it as a hard-wired alternative to Wi-Fi to eliminate dropped connections, using the same type of signal. But to be honest, I have no particular knowledge or expertise about the various signal transmission protocols, Iâve just been tinkering with and building my own computers for 30 years.
If you do decide to give it a try, please report back how it goes.
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Today I was able to pair my Computrainer with Zwift on my newer laptop using the workaround. (Initial pairing that drops, then after in a ride, go to pairing settings, unplug the FTDI USB adapter, plug it back in, and voila .. which only works for some people, sometimes, on some computers.) I can attest that I never saw any of the new pairing screen features (connection type icons, sensor relay beacon), not during the initial pairing that dropped, nor after the second paring that did not drop. (Full disclosure, the pairing dropped two more times, just not right after re-pairing, once about a minute before my laptop gave a low battery warning, and a second time when plugging in the laptop charger. But at least the workaround worked each time so I could continue my ride.) Here is why this behavior fits with my theory of the new pairing screen features being the problem:
Initial successful paring with the Computrainer, then Zwift queries the connection signal type. Not seeing any connection signal types it is programmed to recognize after looking for 2 seconds, it ends in an error code which terminates the pairing. On some computers and trainers and for those with luck, the error does not trash the ability to pair again with the same trainer, such that with the workaround, you can pair the Computrainer again to Zwift while in a ride. It looks like Zwift programmed the new pairing screen features to only query the connection type on the initial pairing, and not during subsequent pairings while in a ride. So for those that are lucky enough to be able to pair their Computrainer again during a ride, the second pairing attempt works like it used to and is not scuttled by Zwiftâs wonderful new âfeature.â
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Hi folks,
Weâve been able to internally recreate the issue described in this thread and are working to implement a resolution in a future version of Zwift. Iâll leave the workaround marked as a solution for now. Once we have a reliable resolution released in-game, this thread will be updated accordingly.
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Some users may not be able to connect at all because they installed Windows Security Update KB5073724. I temporarily paused updates for a few weeks but Windows 10 just installed KB5073724 on my PC. My CT couldnât connect to Zwift at all after the installation. After I uninstalled this update, Zwift could connect again (not like in 2025). Please check for this update if you canât connect at all.