Devices connected through a USB hub are highly unreliable in host mode

Setting dr_mode = "host"; as described in https://source.puri.sm/Librem5/linux-next/issues/114#note_75117 results in devices connected through USB hubs either not working at all or working unreliably. The setup is: supplied wall wart connected to the power input of the hub using supplied USB type-C cable, hub connected to the phone's type-C port.

Both the j5 Create JCA374 and Startech HB30C3AGEPD show similar behaviour, with devices not accepting USB configurations, disappearing from the bus, drivers for connected Ethernet adapters complaining about not being able to read device registers, etc. For example:

Feb 10 11:15:31 pureos kernel: usb 2-1: USB disconnect, device number 2
Feb 10 11:15:31 pureos kernel: usb 2-1.3: USB disconnect, device number 3
Feb 10 11:15:31 pureos kernel: device: 'ep_81': device_unregister
Feb 10 11:15:31 pureos kernel: PM: Removing info for No Bus:ep_81
Feb 10 11:15:31 pureos kernel: device: 'ep_82': device_unregister
Feb 10 11:15:31 pureos kernel: PM: Removing info for No Bus:ep_82
Feb 10 11:15:31 pureos kernel: device: 'ep_03': device_unregister
Feb 10 11:15:31 pureos kernel: PM: Removing info for No Bus:ep_03
Feb 10 11:15:31 pureos kernel: bus: 'usb': remove device 2-1.3:1.0
Feb 10 11:15:31 pureos kernel: ax88179_178a 2-1.3:1.0 enx00051b60b62d: unregister 'ax88179_178a' usb-xhci-hcd.3.auto-1.3, ASIX AX88179 USB 3.0 Gigabit Ethernet
Feb 10 11:15:31 pureos kernel: ax88179_178a 2-1.3:1.0 enx00051b60b62d: Failed to read reg index 0x0002: -19
Feb 10 11:15:31 pureos kernel: ax88179_178a 2-1.3:1.0 enx00051b60b62d: Failed to write reg index 0x0002: -19
Feb 10 11:15:31 pureos kernel: PM: Removing info for No Bus:enx00051b60b62d
Feb 10 11:15:31 pureos NetworkManager[539]: <info>  [1581333331.7947] device (enx00051b60b62d): state change: unavailable -> unmanaged (reason 'removed', sys-iface-state: 'removed')
Feb 10 11:15:31 pureos kernel: device: 'port0-partner': device_unregister
Feb 10 11:15:31 pureos kernel: PM: Removing info for No Bus:port0-partner
Feb 10 11:15:31 pureos kernel: ax88179_178a 2-1.3:1.0 enx00051b60b62d (unregistered): Failed to write reg index 0x0002: -19
Feb 10 11:15:31 pureos kernel: ax88179_178a 2-1.3:1.0 enx00051b60b62d (unregistered): Failed to write reg index 0x0001: -19
Feb 10 11:15:31 pureos kernel: ax88179_178a 2-1.3:1.0 enx00051b60b62d (unregistered): Failed to write reg index 0x0002: -19

Feb 25 13:39:50 pureos kernel: usb 1-1.1: reset full-speed USB device number 3 using xhci-hcd
Feb 25 13:39:50 pureos kernel: usb 1-1.1: Device not responding to setup address.
Feb 25 13:39:50 pureos kernel: debugfs: Directory '04' with parent 'devices' already present!
Feb 25 13:39:50 pureos kernel: usb 1-1.1: Device not responding to setup address.
Feb 25 13:39:50 pureos kernel: debugfs: Directory '04' with parent 'devices' already present!
Feb 25 13:39:51 pureos kernel: usb 1-1.1: device not accepting address 3, error -71
Feb 25 13:39:51 pureos kernel: usb 1-1.1: reset full-speed USB device number 3 using xhci-hcd