If i understand your right, you want packets sourced by 212.31.272.55.xxx be directed to R1 rather than using the default route of R4, to accomplish this you'll need PBR (Policy based routing), apply it to eh LAN interface of R4 and to the interface between R4 and R5, this PBR shall direct any traffic sourced from the 212.31.272.55.xxx range to R1.
I mean if we are talking about the 220.127.116.11/19 subnet all that we are going to do is on the input interfaces of R4, we shall to PBR that directs any traffic sourced from this subnet 18.104.22.168/19 (coming from R4 LAN, or from R5 or R6) to have a default next-hop directing it to R1.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...