Recently OpenStreetMap changed their tile usage policy and require UserAgent string in the web headers for accessing tile.openstreetmap.org tiles.

https://operations.osmfoundation.org/policies/tiles/

As a result, standard open street map mode does not work - no tiles are loaded and "too many requests" error is returned from the server.

RadMap's OpenStreetMapProvider needs API (event, property or similar) for easier set up of UserAgent / Referer / other headers of web requests.

Currently, the workaround is to override the OpenStreetMapProvider like so:

    public class CustomOpenStreetProvider : OpenStreetMapProvider
    {
        public CustomOpenStreetProvider()
        {
            OpenStreetMapnikSource osmMapInkSource = this.MapSources.Values.ToList()[0] as OpenStreetMapnikSource;
            if (osmMapInkSource != null)
            {
                osmMapInkSource.WebHeaders.Add(System.Net.HttpRequestHeader.UserAgent, "your custom user agent string");
            }
        }
    }