It is possible your router supports hair-pinning or (NAT loopback).
When it detects you are trying to access the external IP address (even if it is cg-nat) it is smart enough to router the data basin internally and some are smart enough to apply firewall rules as well...
Hate to say this (being an iPhone user) but the Android apps are way better :-( If you can face using one try https://play.google.com/store/apps/details?id=com.manageengine.wifimonitor
Apple ~~tweaked~~ crippled the API used by the tools on mobiles a few years ago and quality of results dropped dramatically even for home use.
If you have a MacBook try https://www.netspotapp.com and request the free trial (no obligations is their byline) but TBH its worth the entry cost (£144) to allow you to check the results of the changes and redo each time the office moves around :-) The results are way better (i.e. more accurate) than on a mobile app.
No matter the way you go (I lean to copper less you fancy trying to use pre-made fibre cables) then make sure:
I've been using ICY BOX on an old 2012 Mac mini for years and would happily use Yottamaster kit for the same task. My third option would be G-Technologies.
Not keen on hardware RAID built into enclosures but I've had raid controllers AND software RAID fail on me before today.
Just noticed it's a TalkTalk router (and then felt sorry for the OP).
Their forum says the error is the router cannot log in to the network. Could be fried or an account problem (if not a general network outage). If the reset has deleted the account details they may need TT to help with the settings / password in any case.
Will stick to my original point and with them luck!
Any reason you have not called your ISPs help desk?
Do you really need an SSD if there is only you watching things?
I can happily stream off a single NAS HDD to three users without straining things!
Simultaneous charge and supply circuits cost a fair bit to design and implement.
It's a lot cheaper and profitable to build a basic 'brick' that can be sold to hundreds of thousands of 'phone users rather than a premium product for a few computer folk.