First ensure you testing on LAN and not Wifi.

RB951 can route around 300mbps and 600mbps with ROS v6.35. But that's with more or less default config, no qos and few firewall rules. Did the person who sold it to you say it was good for 500mbps?

Anyway what version of ROS are you using? If older than 6.35, update and try again.

Are you on default config? Can you post it?

The routing speed of the RB951G has nothing to do with the GBe ports. It is determined by how fast the CPU can route. Someone in the Mikrotik thread here tested the RB2011 at 680mbps (with PPPoE & NAT). But it's only able to achieve this speed if Fasttrack/Fastpath is active. Without that, about 300mbps max. The CPU is just not fast enough

Without more insight into your router's config, it's difficult to say why you're only getting 290mbps.

Whoever recommended you the RB951G for 500mbps is misinformed. Even if you can get it to run at 680mbps, that doesn't give you much space to work with. A few QOS or firewall rules will push it back down.

Unfortunately I don't have TIME Fibre to fully test it out.

Further reading:
http://wiki.mikrotik.com/wiki/Manual:Wiki/Fasttrack
https://forum.lowyat.net/index.php?showtopi...post&p=79277123