Hello! I know that there are very few situations like this, but maybe somebody will help...

My computer PC1 is on LAN1, using router1 as default gateway. There is also a router2 on LAN1, which is the gateway to LAN2. When I send a data to PC2 (on LAN2), they are sent to router1, then to router2. There is no ICMP redirection sent to PC1! I was trying ping during watching Wireshark. It was working in RouterOS 5.x a long time ago and I was not checking it for a very long time. Now I use RouterOS 6.29.1. Send-redirects on the router1 is set to yes, of course.

I was testing this more and there are some strange things... The router1 had very long uptime. I turned off all firewall rules, redirections was still not working. I turned on firewall back and redirections started to work and they are still working after reboot. So it seems like ICMP redirections sometimes stop to work. I don't know when.

Why not connect R2 to a different interface of R1 and route LAN2 via R2 in R1? It's situations like yours which caused me to avoid multi-gateway LANs a long time ago.

If you want LAN1 <> LAN2 to work even if R1 fails, you could connect both routers to both LANs and use VRRP on both sides, and make R1 the primary for LAN1 and R2 the primary for LAN2...... This would eliminate the ICMP redirects, give direct-to-router reachability for both paths, and allow some redundancy as well.

(just a thought)