Albert Barnes Commentary Numbers 3:26

"and the hangings of the court, and the screen for the door of the court, which is by the tabernacle, and by the altar round about, and the cords of it for all the service thereof." — Numbers 3:26 (ASV)

the cords ... the service thereof - that is, of the tabernacle, not of the hangings of the court, for these, with their cords and other fittings, belonged to the charge of the Merarites (Numbers 3:36–37). The tabernacle was under the care of the Gershonites.