GL.iNet GL-AXT1800 Tethering to another router

I am trying to get USB tethering to work

1.USB tethering on GL.iNet GL-AXT1800.
Once “USB tethering” connects and has IP ADDRESS . I try to connect one of the GL-AXT1800 Lan ports to TPlink mr600v2 sim router WAN port. The TPlink mr600v2 Wan port will not pickup the connection when I try to connect in the web admin section. (image 2 tplink STATUS will say “DISCONNECTED” greyed out table)

2.Ethernet Tethering If i use my S21FE5G phone and Ethernet tether to the GL.iNet GL-AXT1800 and get a Ethernet connection established and do the same thing so ( GL-AXT1800 Lan port to TPlink mr600v2 sim router WAN port) connection is established WORKS fine.

Q) How do I get USB tethering to work, Is this do to with manually setting ip addresses?

images of working (2)Ethernet connection below

STATUS “CONNECTED” greyed out table

I Manged to fix this I think

I went to GL-AXT1800 -->luci -->Network → interfaces

Tethering (usb0 → changed the PROTOCOL to DHCP Client) saved config and restarted and can now connect from the TPLink Mr600v2 Router.

Connection has been solid for 5 hours no downtime.

The TPlink router also has SIM so it has not failed over that sim card.