Slower download and upload

Hi, I have optical fiber coming in my home, then there is a Gateway (CTS HET-3150) and my beloved Mikrotik RB951G-2HnD plugged in it and of course computer plugged in Mikrotik.
When i try the speedtest.net test it shows speeds around 300-400Mbps.
If I plug the same cable directly to Gateway (change my computer MAC address) it shows 600Mb down and 860Mb up.

Today I’ve updated the router (Mikrotik) to v.6.21.1, tried to reset the settings, disabled all firewall rules,…don’t have a clue where the problem is.

Thanks for any help.

/// I know it doesn’t really mater but I’d like to use it’s full potential.

This device cannot pass more when doing nat. If you set it in bridge with fastpath on (no nat, routing or connection tracking) or use switch chip directly it can handle it. But this is probably you don’t want to…

Yeah I looked at the CPU utilization while testing at speedtest.net and it is 100%.
So is there any way to change the settings and have faster internet conenction while still having it working for Wifi and one cable for my PC?
If there is no way it doesn’t really matter. It is still very nice router with tons of stuff to learn.

It sounds like it may be time for an upgrade to an RB850Gx2. Unless you want to go crazy and upgrade to a rack mount unit, CCR or RB1100AH.

Hope it will be able to do the job. So far it has MTU insufficiency problem but hopefully it will be solved by some future ros update.
Edit : it has only doubled throughput so it is not enough for you.