The problem that this happens is simple to solve if using defferent machines for running server and website.Meaning that you have your server to another hosting provider and your website to another hosting provider too.
1)If you have this error in log files daemon always shows a defferent ip than the actual server's ip and is marked as not allowed.
2)The solution is to use the ip the daemon shows in log files as not allowed and put same at hlstatsx page and you will see that this is working fine,but usually maybe that ip is owned buy someone else, if not, you can ask your host to give you that ip if available for your gamerserver.
3)Or a simple solution is just to have another gameserver ip and port from your host and thats all.And a good advise i to check server with your hlstatsx prior buy it.Because the ips of servers usually have conflicts with other servers.
4) Or ask your host to route daemon of gameserver specialy if its rehlds engine so daemon doesnt have conflicts with other ips.
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(Dont ask me how this is possible but it is.)
Example of my error:
S_CONFIG: 51.89.24.248:27015 2021-09-25 14:25:01: - HLSTATSX: HLstatsX:CE 1.6.19 starting... 2021-09-25 14:25:01: - UDP: Opening UDP listen socket on greek-gaming.com:27500 ... ok
2021-09-25 14:27:29: 51.195.117.179:27015 - E997: NOT ALLOWED SERVER: ����log L 09/25/2021 - 12:27:29: Team "CT" triggered "Target_Saved" (CT "4") (T "0") 2021-09-25 14:27:29: 51.195.117.179:27015 - E997: NOT ALLOWED SERVER: ����log L 09/25/2021 - 12:27:29: World triggered "Round_End" 2021-09-25 14:27
7: 51.195.117.179:27015 - E997: NOT ALLOWED SERVER: ����log L 09/25/2021 - 12:27
9: World triggered "Round_Start"
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That ip:51.89.24.248:27015 is my servers ip.
This ip:51.195.117.179:27015 is another's server ip,so if i add that another server's ip everything working fine.Im tracking that server stats out if the blue even if i dont know his rcon password.[ITS INSANE].Thats means there is some conflicts between servers ip and daemon and how daemon reads them.In that case both ips start with 51,and have same port.So if the port is changed or the ip is changed with other starting number other than 51 that works fine too.Thats why the solutions 3) or 4) of mine is the best right now.