Slow copy one way

I have a routerboard 1100 v4.17

copy speeds from 10.20.0.30 ---->10.20.7.51 = 11.2mb/sec

Copy speeds from 10.20.7.51---->10.20.0.30 = 512k/sec

copy speeds from 10.20.0.31---->10.20.0.30 = 11mb/sec

So what these all means is I have good copy speeds when the clients are in the same subnet. If I change subnets, one way copy is horrid.

Any help is appreciated.

Thank you.

I ended up solving this.

My subnet was sharing a physical interface with a vlan. I moved it to its own and the copy speeds are now 10mb.

The MTU is set for 1500 and the L2 MTU is 1598. Is it set to low? Would that be the reason the copy speed was bad one way?