Question PSU Extension Lead Question

Hey all,

I have just bought a UPS to protect my low powered devices e.g router, server and fibre ONT box however in order to protect my fibre ONT I will need to use an extension lead coming from one of the battery powered UPS sockets. I've read various things online but I need some clarification if it's going to be okay to do.

For clarification this is the UPS I have ordered : https://www.amazon.co.uk/dp/B00KHTD2NQ?ref=ppx_yo2ov_dt_b_fed_asin_title

And this is the extension lead I intend to use: https://amzn.eu/d/4GvBB8e

My fibre ONT is behind my desk so it'll need to go around and behind me to plug into the ONT. The configuration will be as followed:

Direct Socket -> UPS -> One Gang Socket Extension Lead -> ONT

Any issues with this?