F5-221 with TERRAMASTER USB A to 2.5G Ethernet Adapter

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I see the other threads have been closed without resolution. I wish I had seen those before making the purchase. However I did purchase the TERRAMASTER USB A to 2.5G Ethernet Adapter in hopes to start building out a 2.5G network.

Terrmaster F5-221
TOS Version: 5.1.67-00214

I plugged in the USB adapter and there does not seem to be a way to configure it. It does not appear in the interfaces through the webui.

This is sold as PLUG AND PLAY Device and it is certainly NOT Plug and Play.

This is the Amazon Description which also calls it out as being compatible with TOS 5.1

TERRAMASTER 2.5G Ethernet adapter: specially adapted for TERRAMASTER X86 TNAS devices with OS above TOS 4.2.39, or TOS 5.1 and above (NOT compatible with TERRAMASTER F2-210 & F4-210). Connect the Ethernet adapter to a TNAS's USB 3.0 host to obtain up to 2.5G bandwidth on your TNAS. Take full advantage of your high-performance networking devices without having to upgrade your cables.

logging in through ssh I do see it listed in the devices doing a lsusb -v

Bus 002 Device 002: ID 0bda:8156
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 3.20
bDeviceClass 0
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 9
idVendor 0x0bda
idProduct 0x8156
bcdDevice 31.00
iManufacturer 1 Realtek
iProduct 2 USB 10/100/1G/2.5G LAN
iSerial 6 001000001
bNumConfigurations 3
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 57
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xa0
(Bus Powered)
Remote Wakeup

ip addr shows this:

12: usb0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether <removed>

if I manually put settings in /etc/network they are ignored

usb0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet6 <removed> prefixlen 64 scopeid 0x20<link>
ether <removed> txqueuelen 1000 (Ethernet)
RX packets 8491 bytes 474618 (463.4 KiB)
RX errors 0 dropped 8 overruns 0 frame 0
TX packets 566 bytes 107899 (105.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

Disconnecting eth1 figuring maybe there's something in TOS that limits it to just 2 interfaces being active also did not work.

Configuring the interface's IP address, netmask using ifconfig does bring it up, but the setting does not persist between reboots.

usb0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet <removed> netmask 255.255.0.0 broadcast <removed>
ether <removed> txqueuelen 1000 (Ethernet)
RX packets 170188 bytes 7925111 (7.5 MiB)
RX errors 0 dropped 50 overruns 0 frame 0
TX packets 49 bytes 2078 (2.0 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

Also it seems the ifconfig or ip link set commands does not allow setting MTU.

ifconfig usb0 mtu 9000
SIOCSIFMTU: Invalid argument

ip link set dev usb0 mtu 9000
RTNETLINK answers: Invalid argument

For something that is supposed to be plug and play, and just work, this is very frustrating.