NightHawk R7000 and GS 105 and GS108 switches connection problems

I'm using three Netgear devices on a Virgin Media cable modem internet connection.

I've recently had short unplanned (1/2-1hr) power outages while I was having smart meters fitted, and independently some internet connection interruptions.

Now my R7000 router can't see any hard-wired devices on the other side of my two switches, and my wireless devices connected via hard wired WiFi access points work either sporadically or not at all. The Access points are a Buffalo router configured as an access point, with DHCP disabled, and TP-link Nano Wireless Access Point also with DHCP disabled.

If I connect any of the hard wired devices directly to the router Ethernet sockets, the device becomes visible in the Router controls via a browser as an Attached Device.

If I connect it via either switch, it becomes invisible to the router.

One post on the Netgear support forum suggests that after a firmware upgrade, Attached Devices don't always work until you do a factory reset, and re-enter all your former settings. I hadn't upgraded the firmware for months before these issues started, a week or ten days ago, but have since both upgraded the firmware (today) and then reset the router to factory defaults. 

Things still aren't working if connected via either switch.

I have in turn:

- turned off WiFi and disconnected two ethernet-connected WiFi access points

- rebooted the router (more than once)

- powered both switches off and on again (more than once, after any change to wire plugging)

- updated the router firmware to v1.0.11.128_10.2.112 from 1.0.11.100.2.(something)

- factory reset the router after updatingthe firmware

- changed the router IP address back from the default 192.168.1.1 to 192.168.0.1 as it has been for years, and rebooted it

- reconnected to the router via my desktop (iMac) Chrome browser and confirmed which devices are now attached - only two of what should be half a dozen or more wired devices on the 'other side' of the switches.

WiFi attached devices in the same room as the router work and can get internet access when the router WiFi is on.

WiFi access via either of two ethernet connected Access Points works sporadically, and after working for a few minutes, the ethernet connection seems to fail, and they lose both local network and internet access. I've also rebooted the access points more than once, after changing router settings.

I'm at my wits send. This network has worked reliably for years, but I have now spent all afternoon and most of the evening trying and failing to get it to work again, and I don't know what else to try. 

Is it likely the switches have been damaged by unplanned power outages? Their lights all seem to work normally when devices are plugged in, but the devices aren't visible as 'Attached devices' and don't show up in Finder on the iMac as on the network. 

The manual for the GS108 says it doesn't matter to which port on the switches I connect the up link to the router, as it auto-senses that. I've tried more than one, without it appearing to make any difference.

What else can anyone suggest? I think I've worked systematically at this, and am gradually forced to the conclusion that the switches have been damaged in some way.

And one of my WiFi controlled lights has been turning itself off for a few seconds at random, several times in a couple of hours. And it's connected in the same room as the router.