Should be - next time you could try swapping sim between devices, it may be the actual antenna of the devices causing the difference you're observing.

@xlinknz Is it by any chance a RBI site?

Edit: Just checked gis.geek it is a RCG site and only supports 700Mhz 4G / LTE

1 transmiiter 700Mhz and if your hardware does not support this band then you are out of luck

Thank you all for your replies

The 3 phones were a Samsung S21 FE 5G (my work phone), a Huawei Mate 8 (wifes) and an Apple SE 2020 (sons)

None got a VHM signal on 2,3 or 4G. I also sent a SMS from the S21 (via WHM) which wasn't received by the other 2 handsets

The S21 also has a Spark SIM which was ok but as said none got a signal or connection on WHM