2 AP can't see each other networks

RouterOS Beginner Basics
1

I have this setup:

  1. MikroTik hEXs is connected to internet is main router
  2. I have two D-Link DIR-825 Wireless routers connected to Mikrotik via LAN.
  3. On both D-Link routers I have disabled DHCP.

Currently I am facing these problems:

  1. If I am connected to 2nd router, I cannot access first router devices via IP, however I can using hostname.
  2. First router works stable, but second router randomly stops working propertly. Sometimes internet access does not work, or external DNS resolution is slow.
  3. I was once in situation where even on same network connected to first Dlink I was not able to access other device via IPv4, pinging it’s host name would return IPv6 address and that would work. However after some time IPv4 started working fine again.

I am not sure yet, but failures on second router seem to be related to DHCP lease time, after lease expires it’s stops working.

Some more configuration details:
All mikrotik router ip ends with ##.11, first router is ##.12 and second is ##.13