Wifi status no longer shows bytes sent received after update

Which 'major update' would that be @tomhollow? A Features Update (say, from 1703 to 1709) or a cumulative update? I'm guessing by 'major' you mean a Features Update.

I'm on the latest public version of Windows 10, version 1709, os build 16299.371. Run Winver to see what yours is.

I don't know where you were looking at bytes sent and received until now, but I see it where I have always looked before.

Open Task Manager. If it says 'More details' at the bottom then click on that. Now select the 'Performance' tab then select the WiFi, you'll see a graph of activity and beneath that the instantaneous send/receive speeds. Right-click on the large graph and select 'View network details' for more detailed information.

If that's where you were looking too, then it may be that the update reset Task Manager to its default of 'Fewer details'.

tomhollow said:

I used to right click on the wifi symbol on the bottom right of the task bar, select open network settings, then select (something like) status. This would open up a very useful window with a live update of bytes sent and received. I found this very useful for checking various ADSL2 and mobile networks when they seem slow. Now I cannot find this window.

A right-click on the wifi icon used to offer 'open Network and Sharing Center' from the control panel, it now offers 'open network internet settings' taking you to the Settings app instead. There is a link to the Network and Sharing Center near the bottom of that Settings app page. You can also find the 'Network and Sharing Center' in the Control Panel. It still provides the window you liked to use.

See Network Adapter Speed in Windows 10

You can also get to it, Network and Sharing center, by

Right clicking icon in notification area, Open Network & Internet settings, scroll down the right hand side, click Network & Sharing Center. More clicks than it use to be.