Wireless Joint

I have a modem that base is an RM520N-GL. The case is aluminum and the antenna has panel mounts and are mounted on the aluminum case. I checked with a voltmeter/continuity, and all the 4G/5G antennas (4 total) and 2.4/5.8 Ghz wifi antennas (4x) are all mounted on the same housing and are connected via the case/housing - Is this suppose to be connected ?? arent they suppose to be isolated as individual ? or at least cellular and wifi .
Thanks in advance

Generally they will all reference the same grounding point. I don't think it is an issue for these type of routers and modems.

I could be wrong, but that is my thoughts on it.

The larger problem comes into play with the RF cables crossing over points of RF noise, within the unit itself. Sometimes unavoidable, sometimes not.