Ebay sent me a message:

We take product safety very seriously. We’re reaching out to you because an item you purchased may have been recalled or pose a safety hazard. We recommend that you stop using this product. If you have questions about the item(s), please reach out to the seller or the manufacturer. Item details are listed below.

More specific details are provided below.

Item details: 314131256030 - 300Mbps Wifi Extender Repeater Range Booster AP Router AU Wireless-N 802.11

I have contacted the supplier several times over the last weeks and had no response.

I cannot find a way through the maze to raising the issue with ebay. Can anyone help.