Hi, looks like it might work for the C9! A review of the aforementioned adapter from Amazon:
''Next day delivery brilliant, I don't usually do feed back, this is the first one in about 4 years, but this little USB Ethernet adapter is a total steal at £10, anyone who has a LG oled or any recent TV that doesn't have a gigabyte Ethernet, honestly get this, I was getting about 90mb download speed because LG cheaped out and didn't put gigabyte Ethernet in my LG oled b8 that I paid £2200 for, ridiculous LG outta be ashamed, someone recommended this adapter online, but I didn't think it work as it was only 10 bucks, I've just got it delivered, I'm now getting 180mb download speed, that's a big improvement for 10 bucks, everything just feels a lot quicker especially YouTube, I can't recommend this enough, I didn't paid or anything to say this I'm just a normal guy like yourself''