i have 1 wan connection and a LAN connection. I want the Mikrotik router to switch from 1 to the other when it fails to get internet access.
wan conections:
ether 1 = ethernet by LAN (ip = 192.168.194.0/30) ---->main internet connection
ether 2 = dhcp client for a cable modem/router (ip= 192.168.42.0/24)-----> secondary connection
If internet 1 goes down, make 2 the main until it comes back, i have the ether 1 connection pointing to a public ip by Src-nat because i need to specify outgoing src-address for the packets.
In order for a simple fail over to happen, without load balancing being used, you should simply use different distances for those wan interfaces. In general…
For example, for your wan 1 ether 1 inside the routing table, you should set the distance to 1 and enable the check gateway ping then on the dhcp client for your second wan configure the distance parameter to 2.
If you loose communication with Gateway 1 then Gateway 2 will be used. When gateway 1 is reachable again it will switch back to it. However, if gateway 1 is reachable, BUT gateway 1 for some reason has no internet access, then your router will still try to use the gateway1, because it is reachable, but you will have no internet access.
For such case, you can use some recursive routes, see the example here: https://wiki.mikrotik.com/wiki/Advanced_Routing_Failover_without_Scripting
Or you can use a tunnel like PPPoE for eth 1.
I do have load balance, and the problem i see is what you say, Gateway 1 is reachable even without internet access. Let me check the example and i tell you how it goes