a further update since the experimentation done this morning. for the past ~12 hours since then i've been getting a lot of work done on the laptop, and have **NOT** let it sleep during this time.
somewhat randomly the problem has surfaced again, thus suggesting that sleeping has nothing to do with the source of the problem. i was doing something else for a few minutes before returning to the laptop. the lid was left up, so not sleeping, but it had turned off the screen. i unlocked my account. as best as i can recall, my next action was then to try to check for updates, only to find the command hung and finally failed. the wifi was still connected. i checked the lights on the gateway and they were good, so the internet connection was fine. it became apparent that the connection had gone bad somehow, refusing to let anything through. i've experienced this numerous times before, including, i'm certain, before i even installed iwd, let alone configured NM properly to use it (which was just a few weeks ago). so i turned the wifi off and back on (via the gnome menu), and it was refusing to connect. i captured activity with iwmon whilst trying numerous times to ask it to connect, sometimes turning wifi off and back on, and even waiting a full minute before trying again. it just would not connect. dmesg was showing the same issues as before. i was starting to shutdown some of the apps i had open, but then remembered that sometimes when i've experienced this before it was whilst deluge was running (which was not open this time), and closing deluge immediately fixed the problem. (immediately reopening deluge was not a problem). so i closed a couple of things with no change, then closed evolution, and bang, it connected perfectly fine having done so. so it seems to be the case that something occasionally manages to go wrong and jams up the connection (i'm not sure that it's a complete block on all apps sending messages over the connection, but certainly some), in a way that's linked to one of the running apps, which only gets fixed upon closing that app. i.e. an app (evolution it seems in this case, deluge commonly in others) is obtaining some locked access to the connection and failing to release it, even letting itself get blocked by the failed release of that resource. i've previously researched the problem with respect to deluge and found at least one other person experiencing this problem, which the deluge guys could not get to the bottom of as i recall. note, again, to be absolutely clear, deluge was not running in this instance, it seems to have been evolution this time. if this results from the same exact bug as is causing the originally reported problem, it's a little strange since in the experiments i was doing this morning i typically only had terminal and gedit open. of course there may be things like gnome-online-accounts automatically running in the background (which i have accounts setup in). in fact just in case it's relevant, i frequently get timeout errors and such in evolution relating to failures to fetch calendars and such from google.