Hello,
I am unable to host the US Soils Map on an Enterprise portal, as it is only available on AGOL. Is it possible to get it to Enterprise?
(https://landscape11.arcgis.com/arcgis/rest/services/USA_Soils_Map_Units/featureserver)
Can you register it as an item in your Portal Org, save it with your AGOL credentials? Or is this what you mean by hosting it in AGOL? I've done this the other direction - registering a Portal service in AGOL with my enterprise/portal creds, thus making it available to anyone in my AGOL organization.
If this is subscriber content, you can configure the Living Atlas in your ArcGIS Enterprise to pick up this content too. This will require your ArcGIS Online credentials and you will need to follow this documentation:
If you're still seeing issues, you may need to check that your Enterprise can connect to the service.
This can be done using the checkURL function of the portal, which can be found in
https://FQDN/portal/sharing/rest > Login > Portals > Self > CheckUrl
Provide the URL to the service and click Check URL.
I am running into the same thing with this exact layer. Were you able to find a solution?