I thought that Excel 365 no longer worked with v1 and you must use the Legacy Plugin in Excel. Thats where v2 and ODATA 4 came in they worked with the new connector.
v2 is for 10.2.400 - Since you mentioned it on top I assumed you were on 10.2.400.
v1 does not work with the New Adapter to my understanding or atleast doesnt for me anymore since a Office 365 Update I get a 404 - but Legacy is fine.