I was getting the same alert, not only when using OBS, but Wirecast as well. It showed up on a live-stream directly to YouTube and then, Restream.IO. I don't know what you or others are using for a "computer" but I have this problem occurring on a PC with Windows 11 Pro. Thus, the evidence (for me, anyhow) pointed to an issue on my PC or Internet service. Turned out to be the PC.
The culprit? Windows Defender Firewall with Advanced Security
Windows 11 pro Defender Firewall was "blocking" the output of the livestream from OBS (and Wirecast).
Here's the fix. Again, PC with Windows 11 Pro. You might have a different platform and OS, but do check into its firewall functions.
1) On the taskbar's search-bar, type-in FIRE and the results will show a match with "Windows Defender Firewall with Advanced Security."
2) Click on that wording and you'll see a 3-panel display with "Rules" on the left panel, a "Domain Profile" etc. in the middle display, and an "Actions" panel on the right panel.
3) On the far left panel, click on "Outbound Rules." The middle display changes, and the right display shows "Actions" you can choose for Outbound Rules.
4) On the right panel (Outbound Rules), click on "New Rule." A pop-up window is displayed, asking "What type of rule would you like to create?"
5) The default selection should be "Program. If not, select it. You're going to be telling Windows Defender Firewall to ignore a program and let it "output" stuff without argument.
6) Click on [Next] (bottom right button)
7) New pop-up window appears, asking "Does the rule apply to all programs or a specific program? Click on "This program path" and then browse to where your OBS exe file is located. Mine was in C:/Program Files/OBS Program/obs-studio/bin/64bit/obs64.exe
8) Click (once) on obs64.exe, then click on "Open" on the bottom right.
9) You'll be returned to previous window "...program path..." Click on [Next]
10) And here's the big reveal. A new window pops-up, asking "What action should be taken when a connection matches the specified condition?" Notice the default ticked is "Block the connection."
11) Click on "Allow the connection." Not the "...if it is secure" Just allow the connection!
12) Click on [Next]
13) New pop-up window. "When doe the rule apply?" By default all are ticked. Keep it that way.
14) Click on [Next]
15) New pop-up window asking you to "Name" the rule (I called mine OBS unblock." You also have an option to add a description.
16) Click on [Finish]
17) Close the pop-up windows and try livestreaming your OBS. I cannot guarantee this fix will work for you, but it did for me. Mostly because I remembered a time way-back-when (2017) I started using Wirecast for livestreaming a church service and its streaming display kept going from green to red in its RF icon. Turned out to be the Windows Firewall.
Hope this fix works for you and others.
