I got this problem:
I use firewall to block access to the router from the Internet and my proxy does not work.
so I have found a solution
Make sure you allow established TCP connections with tcp option 'non-syn-only' to the router before blocking everything else. In v2.5, the rule is like this:
'/ip firewall rule input add protocol=tcp tcp-options=non-syn-only connection-state=established'
but, can somebody tell me how can I set tcp-options=non-syn-only in routerOS v 3.7 ???
maybe Im too stupid for this