Hi there. I have discovered that using your online server or the PlantUML addin for Confluence (which I believe also uses the online server) results in not being able to resolve any external !include URL. For example below fails. It works locally on my machine but fails when rendering in Confluence or via your online server.
@startuml
!define ICONURL https://raw.githubusercontent.com/thegippygeek/plantuml-libraries/refs/heads/master
!include ICONURL/common.puml
!include ICONURL/devicons/datadog.puml
DATADOG(datadog, "Datadog", rectangle, purple)
DEV_PYTHON(PyDataConnectAPI, "Data Connect API", rectangle, orange)
@enduml