I don't have access to broadband internet so I've to rely on 4g internet. But 4g internet is not reliable and usually requires me to turn off mobile data and then turn on from the router's internet page/section. So i decided to use another provider of 4g network and bought another 4G router and then connect these togeather in a failover scenario. But I'm facing a problem. So here are the details:

Router-1 MR6400  | in 3G/4G router mode | WiFi off | IP 192.168.0.1

Router-2 MR600 | in Wireless router mode | WiFi on | IP 192.168.1.1

Both have sims from different providers. A single LAN cable is connected from LAN port on Router-1 to WAN port on Router-2.

Now when Router-1 loses internet connection, Router-2 stops using the WAN connection and starts 3G/4G LTE interface. and goes back when Router-1's internet is back up. So far so good.

So the problems. First when the Router-1 is down and 3G/4G LTE interface is turned on in Router-2 then I have no way to login to the Router-1 to restart it (Other than switching Wifi on an connecting to that or connecting LAN cable from Router-1 to my laptop.) I want to be able to access Router-1 via Router-2 even when Router-2 is on LTE interface. Is there a way to configure these in a way that I can do this even when the WAN interface is off.

Second problem is that turning off WAN and starting LTE in the Router-2 when Router-1 internet is down, takes about 45-60 seconds. Is there a way to reduce this.