Need to connect to two different network ranges same time

Here is the story.

my inteet connection gateway and my IP goes as GW: 192.168.20.x and IP : 192.168.20.23x

and if I want to access web mail
GW: 192.168.100.X and IP 192.168.100.2XX

and my local area network GW: 192.168.1.23X and IP 192.168.1.25x

Is there any way that I can access all these networks same time with out changing the IP address and GWs time to time

PS: I have already added some routes but those are not working IDK why

the routes I add

please explain

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