Hello @David Bird ,
You have mentioned that "Most of the differences are metaverse attributes and transformation attributes of built-in inbound/outbound rules. The new server has some attributes that are not present on the current server but also has missing some attributes that are present on the current server." There could be few possible reasons for that.
- You might want to check the attributes to find exactly why they are different. The most common thing that could happen is that, on the new server mS-DS-ConsistencyGuid was selected as source anchor while installation. This may cause some changes in rules that you may see differently otherwise. You will need to manually check this or evaluate the output for the attributes .
- A schema refresh would have been done in the local active directory since the old AD connect server was configured. And schema refresh have caused some new attribute additions and deletions which are evident on the new AD connect server because we have installed the new server recently . You could try to do a schema refresh on the old AD connect server but you need to make sure that no default sync rules have been customized because schema refresh does not touch custom rules which are created by duplication of existing sync rules but they do recreate the default rules as is again . So if your old server have any customization in existing default sync rules , it will be rewitten by default AAD connect configuration of that specific version. Mostly it does not changes much but sometimes you may see small changes .
- The Directory Extensions may be different in both the AD connect configuration due to which attributes are different .
The above are the possible reasons i can think on top of my head and I have linked them with relevant articles. I would suggest you to go through the detailed articles to understand more. I would not says that you have made any mistake but its just a slightly different configuration.If you want to read more changes and bug fixes in the two versions you have you can check the Version release history . even that may give you some more insights. Also without looking at the configuration it is very difficult for anyone to know why some attributes are mapped in a certain way as per the AAD config documenter output. . In this case , I would suggest you to open a support case with us to clarify any doubts before making any changes using the powershell script as you rightly said.
Hope this helps . In case the information provided in the post helps you , please do mark it as answer so that its useful for other members of the community. If you have any further queries , please let us know and we will be happy to help .