Hello,

Am joining this discussion because is the topic is very similar to my problem.

I have been using a TP Link Archer C9 v4 for a while now (firmware is up to date), and on it`s USB 3 port a WD My Passport Ultra 1TB that i am using as a small media server for laptops, phones and TV.

Since the 1TB became insufficient i got the 5 TB version ( type-C + adaptor), but keeps droping it. I made 2 equal partitions on the hard  drive but keeps giving errors when i try to copy on it (partitions are mapped as network drives) and even when i try copying through FTP.

To see the mapped drives i have to log into the C9 web interface and scan for the hdd again.

The new hdd works flawless when connected to my laptop.

Please help

@Kevin_Z 

Sorry for the delay in replying but I have had other things to occupy my mind. Yes the HDD keeps losing the connection via the router and disappears off the network. This happens when using both the USB3 and USB2 connections. I have tested the system using a variety of drives ranging from a 46Gb pendrive through to 1Tb and 5Tb portable drives of different capacities and exactly the same situation occurs with the connection to the router disappearing at indeterminate lengths of time (ranging from 4 - 5 minutes to up to an hour) once any form of transfer load is put on the USB attachment (be it the USB2 or USB3 ports).

In order to reconnect I have to disconnect any drives and reboot the entire system including the router before reconnecting the drives. All the HDDs I have used have worked absolutely perfectly when directly connected to the PC so it is not any fault with the HDDs nor the PC.

I have had an excellent technician (whom I have dealt with a number of times in the past few years and trust implicitly) from my internet provider come in and check the links to the internet etc etc and all is correct there even down to the settings so I cannot see any problem there. This seems to be more of a hardware/design problem and it is extremely aggravating quite apart from the inconvenience caused by this malfunction.

I hope that I have outlined the actual siutation with sufficient accuracy.

@Kevin_Z

 Hello

Both are WD My Passport Ultra. I also noticed random disapearing wi-fi signal  from router; when signal shows up again and i connect, sometimes my mapped sda1 and sda2 drives become sdb1 and sdb2 and obviously i can`t connect to them unless i map those too.

Basically when the 5 TB is connected to the router my whole network is unusable. For the time beeing, i am back to the old setup with the 1 TB hdd connected to the router, and works flawless like before. 

in short: yes and yes

@Kevin_Z 

Thank you, i`ll be waiting