A question about what characterizes the CPD, where the room will not have any server only a firewall and internet modem, can it have wooden cabinets? what does iso 27001 charge?
iso 27001 requires a room for endpoint maintenance, it can be next to the CPD room, there is a prohibition on having wooden furniture inside the room.
ISO 27001 does not prescribe what a data center room is, neither its layout nor internal furniture, so organizations are free to define them as they see fit.
The location you will use as a data center, its layout, and furniture will depend on the related risks and if you accept them or not. For example, normal office furniture may not be recommended, but it is less expensive than datacenter-oriented furniture. Having a separate room for endpoint maintenance can be more secure, but if it is possible to accept the risk related to having communication and server equipment in the same room, it is acceptable by the standard.