According to the PMBOK Guide, 6th edition, section 13.3.2.4, the project manager should use interpersonal and team skills to manage conflicts and foster collaboration among stakeholders. Hosting a meeting is an example of such a skill, as it allows the project manager to facilitate communication, negotiation, and problem-solving between the parties involved. The project manager should also use the requirements traceability matrix, the project management plan, and the project documents to clarify the expectations and responsibilities of the vendor and the infrastructure manager. The PMI-PBA Guide, section 6.2.3.1, also supports this approach, as it states that the business analyst should use collaboration techniques to resolve issues and conflicts related to requirements. References:

PMBOK Guide, 6th edition, section 13.3.2.4

PMI-PBA Guide, section 6.2.3.1