@alejandromr 

Hi,

Try the following.

1) Connect the SenseCAP M1 to your router (not the RE550). The router should now recognize the SenseCAP M1.
2) Get the IP address of the SenseCAP M1 from the router and then log into it and do all the configurations on the SenseCAP M1 that you've wished to do. 
3) As an extra you can assign a fixed IP address to the SenseCAP M1 by utilizing the "Address Reservation" feature that every router should have. That way you will always know the IP address of the SenseCAP M1, because it won't change anymore.
4) Disconnect the fully configured SenseCAP M1 and then connect it to the RE550.

If everything works now to your satisfaction, then consider yourself lucky. In case it doesn't work well, then there is not much else you can do. (apart from replacing the router with one that supports OneMesh or EasyMesh)