I'm leaving an answer because someone may encounter same problem.

Okey, as seen from results from traceroute the packets were "stopped" just before my server. That could mean two things: my firewall or some filtering of outgoing packets on previous server.

As suggested by @BenVoigt I have used iptables -vL command and compared amount of bytes per rule. After few times I was almost sure that the problem is not related to my firewall configuration.

My next step was contacting ISP. After several messages we finally found out why the packets were droping. Somewhere hidden in deep abyss of their configuration panel there was an option of UDP packets filtering which was turned on by default. Turning it off solved problem.

Yep, that's pretty much everything. As I said somewhere in first post, I knew the solution was easy.

I'm leaving an answer because someone may encounter same problem.

Okey, as seen from results from traceroute the packets were "stopped" just before my server. That could mean two things: my firewall or some filtering of outgoing packets on previous server.

As suggested by @BenVoigt I have used iptables -vL command and compared amount of bytes per rule. After few times I was almost sure that the problem is not related to my firewall configuration.

My next step was contacting ISP. After several messages we finally found out why the packets were droping. Somewhere hidden in deep abyss of their configuration panel there was an option of UDP packets filtering which was turned on by default. Turning it off solved problem.

Yep, that's pretty much everything. As I said somewhere in first post, I knew the solution was easy.