Hello,

running the plugin returns this exception:

Web request callback raised an exception in 'Welcomer v1.4.1' plugin (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.Welcomer+c__AnonStorey0.<>m__0 (System.Int32 code, System.String response) [0x00079] in <64c507f8f5904e0eb4ec225d557f5f2a>:0

  at Oxide.Core.Libraries.WebRequests+WebRequest.b__42_0 () [0x00034] in <4452f821def6406d834e4149849fe7ea>:0

No welcome message is sent to other clients but all other plugin's functions work correctly.

Well this was an incredible issue...

The plugin uses http://ip-api.com/json/ in order to determine the country. My rust server was returning code 200 but with an empty response while my client computer was receiving a normal json string.

The issue was a router-level ad/spam blocker that I'm running on my router's custom firmware. I had to whitelist the http://ip-api.com/json/ on my router and everything worked corectly afterwards.