The Ethernet cable between my ET10K and the router was still connected.
The wall wart supplying low voltage power to the router was still supplying power and connected to the router.
The router was switched off with it's own on off switch which to the best of my knowledge completely turns it off. It had been left off for 6+ hours.
I've Just repeated a couple of boot-ups with just the (short) Ethernet cable disconnected at the router end.
First boot 3 minutes.
Second boot
Times below are the cumulative times between the switch on to the end of that sequence
The second and third Vix splash screens on my box have the same image but there is a few seconds of blank screen between them. I have customised boot splash images.
Extrend splash screen 15 seconds
First Vix splash screen 40 seconds
Second Vix splash screen 1 minute 45 seconds
Third Vix splash screen 3 minutes 5 seconds
All other equipment normally connected to the box was still connected and switched on.
Fire stick on the HDMI input (via a HDMI switch)
TV on HDMI output
AV amp connected optically
Using OpenVix 5.1.021.
Note in case its relevant
The Extrend 10K has LAN and VLAN connections. The former is used, the latter isn't.