A plug connector for connecting a cable to a receptacle connector includes a housing (209) comprising an upper housing portion (212) assembled to a lower housing portion (211), the assembled portions defining a cavity (280) within the housing. One or more printed circuit boards (201, 202) are disposed in the housing cavity and a cable (100) is disposed in the housing cavity and connected to printed circuit boards. The assembled upper and lower housing portions define a first housing sidewall comprising an upper sidewall portion (221u) at the upper housing portion and a lower sidewall portion (221b) at the lower housing portion. The upper and lower sidewall portions define a gap (220-1) in the first housing sidewall at an interface between the upper and lower sidewall portions of the first housing sidewall. The gap extends only partially or at least partially along a length of the first housing sidewall.