Two ISP using PBR o not?

[Raymundo]

I would like to make the following configuration:

I have two internet services, (ISP1 and ISP2). I want all the subnets to go through ISP1 and only one subnet through ISP2. When ISP1 is down all traffic send it to ISP2, when ISP1 is going to be up the traffic will return through ISP1. Likewise, if the ISP2 is down, the subnet that goes out through that link will pass the traffic to the ISP1 and when ISP2 is up again, the subnet will go out through SIP2.

Do I have to configure any Redundant SIP? (HA or Load Balancing)
Should the default route be added to ISP1 only? or also to ISP2?
Would you use PBR?

Is it possible to configure ISP2 as a VPN client service?

[PhoneBoy]

You’ll probably have to configure ISP Redundancy for this to work seamlessly due to the need for NAT.
It should support the configuration you describe.
You can use ISP2 as the Remote Access endpoint if you wish, just configure the relevant IP for Link Selection.