WMS maps require several configuration fields to be set up. This can be confusing, but here are some simple notes to help you set it up.
The following image shows the fields to be configured: Annotation 2020-01-08 090215.jpg
Notes on fields:
Source URL - this usually will have no parameters, so will not need to have any / or ? or & characters at the end.
When there is no username and password, the form will still show dots (as above), this is normal.
The names of source layers available in a map service are often available in a metadata description of the capabilities. You may be able to see the available layers and other parameters by appending this to the Source URL and pasting into a web browser:
The above is an example of the parameter values. You can try adding these parameters to the Source URL in a web browser to check the source is valid.
Therefore the CustomData field should not contain the keywords: SERVICE, VERSION, REQUEST, FORMAT, LAYERS, SYTLES, CRS, BBOX, WIDTH or HEIGHT
It is not usually necessary to select 'Request Map as Single Tile
Where map layers are not being displayed, or are showing incorrectly, you can invoke a diagnostic display. This is only available to Administrator users. To open the display after displaying a Map Source or Map Set, left-click the tab of the map, then press the F12 key. The 'Sources' tab of the window will show the images which the browser is loading.