There are two antenna connections for mobile reception. The first input is for 5g SA and is therefore currently of no use to you in Switzerland, as we only have 5g NSA so far. The second is for 5G NSA / LTE. In a review on amazon.de I found the following:
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At first I was a bit desperate about the antenna connection because I thought it wouldn't work. But I have now received an answer from ZTE and have been able to test it successfully:

Frequency bands supported by the interface:
Interface 1: N77/78 TRX;
Interface 2: N77/78 RX, LTE B1/3/7 RX

I can confirm the feedback 100%. I have now carried out various tests by putting the router (for the test!) in a metal money box in a cellar room with extremely poor 4G reception and then mounting the external antenna (in my case the DMM-7-38-2TS9 from Panorama) on the cellar window.

The fact is that port 1 cannot receive a 4G signal via an external antenna, but port 2 can. I then had about 4 times the internet speed with an external antenna (instead of 8Mb/sec then about 32Mb/sec). It didn't matter if both cables were connected or only one.

However, I also found out that the antenna is only useful in situations where the router is in a bad position. With the antenna connected at the same location, no improvement is noticeable. Apparently the integrated antennas of the router are very good and do not need any further "support" and get the signal "directly". This can of course be different with better antennas - especially outdoor antennas.

If my technical understanding is correct, then no MIMO reception is possible with external antennas on 4G/LTE, as only one antenna is controlled. That is a pity.

With 5G, both antennas are controlled, then MIMO should also work.
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