I would try to check with IP first , but your question is a bit more complicated to answer with just "test it with IP".
The issue here is how dynatrace will try to rich out your Remedy service and if you are using SaaS or Managed?
In SaaS, one of your AG will need to get access to Remedy and may be you will need to add the Remedy host to the Exclude hosts from proxy communication list.
In Managed the cluster nodes are also trying to reach webhooks and may be you will need to exclude Remedy host from using the proxy as explained in this thread.
HTH and if not the shortest way IMO will be to open a support ticket
All the best and stay safe