I have a rtac86u running the latest merlin firmware, when i reboot the router all my ports that were forwarded are gone, under open nat for games and wan, port forwarding.
What firmware did you upgrade to this latest from?
Was a full reset performed afterward and then the router was minimally and manually configured? Without importing a saved backup config file to secure the router and connect to your ISP?
Are you running low on resources? NVRAM, JFFS, RAM, etc.?