I use a TL-MR3020 device in «WISP» mode. i.e. I connect the router to a hot-spot (mobile device) and other devices to the router's WLAN.
The router's WLAN accessibility seems to depend on the state of hot-spot connection:
hot-spot (mobile-yfl) disabled: WLAN (citron.brn) ist accessible
hot-spot (mobile-yfl) connected: WLAN (citron.brn) is accessible
hot-spot (mobile-yfl) not connected: WLAN (citron.brn) is NOT accessible
«not accessible» means, it does not show up in the in the list of the available WLAN of the device I want to connect too.
Have you verified that the iPhone hotspot works for 2.4G? If the iPhone is using a 5G radio for the hotspot, it will not work since the MR3020 only has single 2.4G radio. (I haven't checked to see if the iPhone uses both 2.4 and 5G when in hotspot mode, so I don't know the answer to this offhand).
I found the problem meanwhile.
When the iphone hotspot is scanned through travelmate, it connects exactly once. When I disable the hotspot on the iphone an re-enable ist does not connect anymore. This is due to the changing MAC address of the iphone hotspot whenever it reconnects. I need to clear the MAC address stored the first time the hotspot connected: