I encountered a similar issue on the editor and Windows 2022.3.45f1. Is there any solution other than changing the version?

Same issue as https://issuetracker.unity3d.com/issues/tlsexception-handshake-failed-error-code-unitytls-internal-error-error-when-a-lot-of-web-requests-are-sent-within-a-few-minutes. Hopefully this one will be picked up in more detail

I am the lead developer of Cesium for Unity, and can confirm that this issue has a major impact on our mutual users. Our product limits the numer of simultaneous requests to 20 by default (consistent with web browser behavior), but even that is apparently enough to break UnityWebRequest after a time. Let me know if I can help in any way.

I am the lead developer of Cesium for Unity, and can confirm that this issue has a major impact on our mutual users. Our product limits the numer of simultaneous requests to 20 by default (consistent with web browser behavior), but even that is apparently enough to break UnityWebRequest after a time. Let me know if I can help in any way.

I am the lead developer of Cesium for Unity, and can confirm that this issue has a major impact on our mutual users. Our product limits the numer of simultaneous requests to 20 by default (consistent with web browser behavior), but even that is apparently enough to break UnityWebRequest after a time. Let me know if I can help in any way.

I am the lead developer of Cesium for Unity, and can confirm that this issue has a major impact on our mutual users. Our product limits the numer of simultaneous requests to 20 by default (consistent with web browser behavior), but even that is apparently enough to break UnityWebRequest after a time. Let me know if I can help in any way.

I am the lead developer of Cesium for Unity, and can confirm that this issue has a major impact on our mutual users. Our product limits the numer of simultaneous requests to 20 by default (consistent with web browser behavior), but even that is apparently enough to break UnityWebRequest after a time. Let me know if I can help in any way.

(Also posted in forum thread)
Reasons why this is definitely still an issue:

Host limit reduces reproduction time exponentially, so setting a max of 8 will indeed no reproduce it unless you let it run for a few hours. Then you will still get the issue. We use a blockchain game with web requests, limitting to 20 concurrent requests, but it still triggers after 1/2 hours.
The issue did not happen on older unity versions
The issue is not just about not supporting many requests, its about the entire request service breaking and not allowing any new connections after triggering the issue, forcing the user to fully restart the game/editor.
It even triggers in the editor if using web requests for other stuff like analytics (yes including unity analytics), but it might take multiple hours, we generally experience it once per day (8 hours), even after rewriting our entire blockchain interaction to use HttpClient rather than Webrequests (as that one does work)
The resolution mentions the browser, but suprisingly, the issue does not uccor when running in the browser using webGPU. It occurs in the editor and standalone PC builds.
My guess is that something in the internal unity webrequests handling is not cleaned correctly and you slowly use up sockets until there are non left for the application, then any new ones fail as all slots are taking by broken connections.

Excuse my directness, but I am sad and suprised to see the issue closed as “By design” for such an incredibly impacting issue. We had to rewrite to use HttpClient to somewhat prevent the issue, otherwise our players wouldn’t be able to play for longer than ~1 hour. And again, this was only after upgrading unity. How can this be by design?

Especially with the upcoming WebGPU stuff, this will be problematic as Travian-like games will be impossible to make using traditional Web Requests, and the web is not really that well optimized for multi-threading to enable sockets—super bad move.

We are currently seeing this in a game we're making. It's an online game with a lot of API calls back and forth so it's bound to have a lot of web calls.