Hello, there is a comment from the MTA Staff about this problem, I would like to ask you that if this is on a specific server, all you need to do is contact the owner of that server and the location where the server is hosted may not match your DNS or may be blocked, if you have this problem on all servers, read my comment below
Please download and run this file (rightclick > run as Administrator): https://mirror.multitheftauto.com/mtasa/utils/servicing.bat (known to have fixed most CD16 error cases without ability to connect anywhere) and then restart your PC before trying again.
Still not fixed? then completely disable Windows firewall/any third-party firewall, as CD16 means MTA traffic is being blocked by something. It's not a good long-term solution, but if whitelisting MTA doesn't seem to work, see if its caused by Windows firewall at all, by disabling its service (start > run > services.msc > rightclick Windows firewall service, select state ''disabled'' and Apply, then hit ''stop'' service button)
If after that the problem persists.. then;
Please download and run MTADiag and follow the instructions.
Create a new topic in the "Client" section and paste any Pastebin URL MTADiag gives you in said topic.
Also if you want to know more about CD16 error, read this: https://forum.multitheftauto.com/topic/95511-error-cd16/?do=findComment&comment=855986
As stated there, the problem can either be caused by something with your OS, or your router/network. Feel free to try with another PC if you have one, on the same network, if that works you can first try with the .bat file to reset your PC's networking stack etc, / we'll continue troubleshooting from the MTADiag log once you post it, and if the second PC encounters the same CD16 error, it's likely your router, for which I will provide instructions to try solve that after you post your log. (as I can get the router's configuration page from there, but if you already know how to access it; go there, (the address is 'Standard gateway' from network properties or ipconfig /all, then put it in browser) login with default user/pass for your router's model, and disable/lower level of the routers internal firewall. If that still doesn't work, try enabling DMZ zone (also found in router configuration somewhere) for your PC's local IP, and then set that PC to static IP by mac or device.
This post may seem a bit huge though, but it's because I will likely cite it for future CD16 error support.