Question about 4smarts VoltHub

I have tested it with myself: I can charge e.g. 2 IPhones during charging (e.g. one wireless and one via USB, or both via USB). Alternatively, an XPS13 notebook (PD USB-C with 45W). However, when the XPS13 notebook is connected, it no longer charges at the other sockets - I suspect that with charge-through, the charging power is not as high as usual.