Basic Networking Help

I am in the process of replacing our aging equipment with new Aruba 6200, 6300, and 6400 series switches.

I'm having trouble getting the new switches communicating with the old switches.

Old switch (port14) ---- New Switch (port 1/1/42)

oldswitch

interface 14

name newswitch1

interface 23

name mdfswitch1

interface 24

name mdfswitch2

vlan5

name clients

untagged 1-20

vlan30

name management

ip address 10.10.30.35 /24

vlan 900

name interswitch

untagged 23-24

What I did for now was add port 14 to vlan 900 as an untagged port

vlan 900

name interswitch

untagged 14,23-24

I then setup a basic config on the 6200 series vlan 5 name Client vlan 30 name management vlan 900 name interswitch interface mgmt no shutdown ip static 10.10.30.7/24 default-gateway 10.10.30.1 nameserver 10.10.18.16 10.10.18.15

It appears at this facility all the switches are connected to one another via vlan 900 and their ports are untagged.

Going from the older hp / aruba series to the newer series.. i thought i'd have to use the following command

int 1/1/42

no shutdown

vlan access 900

That did not work.

I then attempted to create a trunk on both devices

oldswitch

trunk 14 trk1 trunk

new switch

int 1/1/42

vlan trunk allowed all

I still wasn't able to ping the management interface or the default gateway

What am I missing?