I DO NOT know anything about the EA2700 but AFAIK tis 'bout same as E2500 only EA2700 has 480 MHz CPU vs E2500 300MHz.
If it is like the E2500 then you can look at my post here ---
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=320028 see my link in post to webif pages & notes
NOTE: I have port 4 (LAN port beside the WAN) as VLAN4 together with wl0.1 via br1
Last time I set this up from scratch was with r41997 and worked just fine.
However because of the broadcom VAP-crap now days I also had to use this set in webif startup. ,,, my notes:
# startup in GUI so VAP will work:
wlconf eth1 down
wlconf eth1 up