Have there been any updates that address the problem of Chromebooks connecting to USB Drive plugged into C7 routers.  It appears to be an SMB level issue, as indicated by posts in an earlier thread on this topic.  Specifically,

What I found is that Chrome OS can natively mount the file share if the protocol level is SMB3_11, SMB3_02, SMB3_00 or SMB2_10, but mounting fails if protocol level is set to SMB2_02 or lower.

Now, the C7 with the latest firmware is running Samba Version 3.6.25, whose maximum supported protocol level is SMB2_02 and hence mounting an USB disk connected to the C7 in Chrome OS does not work.  Google has withdrawn previous third-party apps that provided a "workaround."

Samba Version 4.x has been available for about 9 years and does support higher SMB protocol levels, but that would require the router manufacturer to integrate it in their firmware.

Response from TP-Link on 2021-01-06 20:47:59

Re:Accessing USB storage Device from a Chrome book

Thank you so much for the dedicated testing and sharing. We will also report this to the dev team and ask them to investigate further then evaluate if we can integrate higher SMB protocol on the Wi-Fi routers.

Thanks again for your efforts, good day.