Mac Persistently Connecting to Personal Hotspot

I realize this has been asked in several variations but nothing I'm trying is working.

Every time I bring my iPhone into my office or try to charge my Apple 6 watch in my office, my Mac insists on trying to connect to the personal hotspot. This disrupts the internet connection and the only way I can get it back is to turn off WiFi through Settings and back on again and manually choose the router (sitting right next to the Mac.) This is, to put it mildly, deeply annoying because it interrupts work.

The things I have done:

Gone through the whole 'Forget a network on Mac' instructions many times.

Instruct the Mac to join the router automatically. All other nearby possibilities, including extenders, have been excluded or removed through Settings. The Mac obeys this regarding other networks. But the minute I bring my phone into my office, it drops the router and sits around confused, not connected to anything. If I delete the hotspot via the 'Forget Network/Remove' and manually reconnect to the router it is fine until I bring my phone in again or put my watch on the charger. Then up pops 'torey's hotspot2' or 'torey's hotspot15' depending how persistent the Mac and I are with each other.

I have entirely turned off the personal hotspot on my phone.