slow ip sec

Senario

Office
RB1100 with a 30 meg link

Home1
6 meg down dsl (generally get 5)
uses routing to talk bi directional to office

Home2
lte (generally gets 30+ down)
uses nat with rdr rules for backup appliance

Both houses
rb752u
l2tp
ipsec sha with 3des

Want to use link for remote backup to the lte location. So just concerned about speed from office to home.

When we copy from office to home we only get 1-2 meg.
This includes changing sha 3des to md5 aes-128 and turning off ipsec.

What can I try to speed up the link?

Thanks
Tom

changed mtu to 1388

now home1 can bw test at 5 meg not over ipsec .5 over ipsec

home2 can get 15 and 2.7

Thanks
Tom