when you have more free time, you can read this: MT filter
Good practice: configuration
It will be useful, you can safely use it and it will be your solution to the problem. As for your question, everything is relatively simple there. To ensure stable and correct traffic operation, you need to create a correct traffic flow. In your case, the error is in the firewall filter section. You are missing the necessary entries that ensure not only correct traffic flow, control, etc., but also security. In Mikrotik, the firewall policy is executed from top to bottom. First, the ''Input'' chain, then the ''Forward'' chain. The order of the rules also matters, because incorrectly grouped rules affect both security and traffic quality. This is not only in Mikrotik routers, but also in enterprise solutions. Input chain indicates what you will allow to enter your router, but forward chain - everything else that passes through your router. Forward chain also indicates subnets that will be accessed or denied and which will have access to the Internet. And for the policy to work correctly, the last rule in both the Input chain and the forward chain is drop=All.
Good luck!