[Galaxy S6 Edge General] doedoejohn:
I found a way to enable Ethernet over USB OTG on a Samsung S6 Edge (SM-G925I, International Edition). The phone needs to be rooted because the method requires enabling the interface and editing routing tables.

The method has a "high" level of difficult, because it requires to enter commands on the phone using a terminal. By sharing this method, I hope experts will be able to automate this process, e.g., via an app.

While the description is for the Samsung S6 Edge, I suspect that this method may also be used on other phones.

Pre-requisites:

Tested on Samsung S6 Edge, SM-G925I, with Android v5.0.2 (Build LRX22G.G925IDVU1AOE3).

Phone must be rooted. This is necessary because you will be editing IP routing information which is only available with superuser access. Instructions for rooting the phone may be found elsewhere in XDA.

Set phone to "Airplane Mode" with Wi-Fi disabled. This simplifies the setup, but it is possible to lift this restriction. Left as an exercise to the reader. :D

Connect the phone to a micro USB OTG adapter. Then, connect the USB OTG adapter to a USB to RJ45 Ethernet adapter. Then, connect the Ethernet adapter to a router. (I have had good luck with BobjGear connectors and adapters. Sold by major online merchants.)

Setup

Your setup should look like this:

Samsung S6 Edge <-> Micro USB OTG connector <-> USB to RJ45 Ethernet adapter <-> Router <-> Internet

Enabling USB OTG interface

Using an app such as "Terminal Emulator" (by Jack Pavlevich) enter the following commands:

Check whether phone can reach router (that is, the gateway). Note: use the IP address of your router. Output shows that phone does not have access to any network.

$ ping -c 3 192.168.1.1
connect: Network is unreachable

(Optional) Check existing routing setup, useful for comparing after setup is completed.

# ip route // Should not show anything
# ip rule // Shows default rules (in my case, there are eight)

Confirm that the interface is visible to the phone.

$ netcfg
eth0 DOWN 0.0.0.0/0

The "eth0" interface corresponds to Ethernet over USB OTG. "DOWN" means that "eth0" is not active, resulting in the "Network is unreachable" message when pinging the router.

Now, gain superuser access:

$ su

Enable "eth0" interface. Router must be setup for DHCP.

# netcfg eth0 dhcp

If above command times out, try again. Otherwise try:

# netcfg eth0 down
# netcfg eth0 dhcp

Confirm that the interface is up and it has been assigned an IP address by the router. (IP address assigned to "eth0" will vary depending on your router setup.)

# netcfg
eth0 UP 192.168.1.21/24

Now, ping the router. (Note: Use your router's IP address.)

# ping -c 3 192.168.1.1
Network is unreachable

While interface is active and it has an IP address, phone still does not have access to any network. :confused:

Let's examine existing IP routing settings:

# ip route

The above command does not show any output, indicating that no IP routing is set up. In devices that support Ethernet over USB OTG off-the-shelf (e.g., Nexus 5, Sony Xperia Z1 phone and Z2 tablet), IP routing is setup "automatically". But in devices such as Samsung S6 Edge, IP routing settings need to be enabled manually using the commands below. (My guess is that Google, OEMs or carriers do not want you to use Ethernet over USB OTG.)

Configure IP routings

Configure IP routing in the "eth0" interface. The settings are similar to the ones used by the phone when the Wi-Fi interface is enabled. If the settings below do not work for you, check the IP routing settings on your phone when Wi-Fi is enabled and "eth0" is disabled, and adjust accordingly.

# ip rule add from all fwmark 0x101f9/0x1ffff lookup 1024 pref 13000
# ip rule add from all oif eth0 lookup 1024 pref 14000
# ip rule add from all fwmark 0x1f9/0x1ffff lookup 1024 pref 19000
# ip rule add from all fwmark 0x0/0xffff lookup 1024 pref 22000
# ip route add table 1024 192.168.1.0/24 dev eth0
# ip route add table 1024 default via 192.168.1.1 dev eth0

Exit superuser mode and (optionally) confirm IP routing settings.

# exit
$ ip rule // Command should show new entries 13000, 14000, 19000 and 22000

(Optional) Examine new IP routing settings and and newly created routing table entry.

$ ip route show table 1024
$ ip route

Both commands should output something like this:

default via 192.168.1.1 dev eth0 proto static
192.168.1.0/24 dev eth0 proto static scope link

Finally, confirm router is reachable from phone. (Note: use your router's IP address.)

$ ping -c 3 192.168.1.1

That's it! Your phone should now have Ethernet access over USB OTG. :cool: Enjoy!

Ps. Please hit 'Thanks' if this info was useful.