Options for bridgeing to 5G network while Broadcasting 5G Network? MT3000

I bought the MT3000 router because I am in a situation where I have access to a mixed 2.4/5G WiFi network as my primary home network. I do not have access to any of the router settings etc... just an SSID and PW to use this mixed network. I have quite a few devices and I want to be able to do things like give them static IPs, use some wired and some wireless with 160mhz channel bandwidth. Basically I want to build my own private network that uses the main WIFI network for internet access.

I am running the mt3000 in network mode with a bridge to the main mixed 2.4/5G WiFi network. I can not tell the bridge to use the 2.4G radio to connect to the main WiFi, so it automatically connects as a 5G client. This means I can not change the channels or bandwidth of the 5G radio, it just automatically defaults to the same settings as the main network the bridge connects to. I also have problems using the 5G network, for example if I run speedtest.net while connected to the MT3000s 5G network the whole router crashes and resets, I do not have this issues when I connect to the MT3000 2.4G network.

Is my only option to use an external WiFi to Ethernet bridge connected to the WAN port, if I want control of the MT3000 5G settings, and to stop the crashing? Is there any way I can connect a USB WiFi 6 dongle to the MT3000 USB port that way the Bridge and WiFi Lan are on seperate radios? Am I just configuring the router wrong maybe?

Is the Repeater’s ‘Allow Switching’ and ‘Band Selection’ options what you are looking for?

On the main GL GUI Internet page, click on the cog ICON for Repeater Options to disable Allow Switching and set the Band Selection to the band you want. Then disable that band on the Wireless page for the LAN.