@StrikerRon 

Hi, As the error code 89534: no available band when you try to manually select the LTE bands on 3G/4G routers, here are useful suggestions shared by our users.

1. If you are using external antennas, such as LPDA and OMNI type, please pay attention to the LTE frequency of the external band since they might be out of the LTE frequency range on 3/4G routers, and please try to select LTE bands under the original antennas.
like #5 Jprathap mentioned here:

2. Turn off mobile date under Basic>internet>mobile data or Advanced>network>internet>mobile data; then try to select the LTE bands again.

like #21 mib896 suggested here:

3. If your LTE gateway(like MR150 v2) does not support manual band selection yet, please install the beta firmware on this link:

[Solution] Manual Band Selection for 4G WiFi Routers

4. If your issue actually is: Archer MR600 V2 was working before, then after a reboot, it cannot use the 4G network anymore.
Under 4G preferred mode, it only connects to WCDMA which is a 3G network(if the carrier doesn't support 3G anymore, the internet will not work). When trying to change Network Mode to 4G Only and save it, Error Code 1: Internal Error pops up, Besides, when searching 4G band manually, it shows "error code：89534 no available band"

Please refer to the solution on this link:

[Solution] No connection in 4g after reboot

While in case your case is related to neither of them, please feel free to start a new thread with more details about your issue!

Thank you very much.