The question of the day is " whats onboard the laptop for a Wifi adapter". Realtek, Intel or other?
There might be more than one problem afoot. If the laptop or any other device reports that its only capable of running on a 2.4 Ghz network, and the modem insists on kicking it over to the 5 Ghz network, then there's an issue with the modem firmware. That should be a basic quality control check. One of those "what if" questions that should be answered prior to version acceptance. In this particular case, if the device indicates that its only capable of using 2.4 Ghz networks, and the modem attempts to run it via the 5 Ghz network the end result would be a connection failure.
The follow on from this is, "what if the modem doesn't run the device at its stated capability, so that the user has to resort to downgrading the device to 802.11g rates". That might resolve the problem, to a degree, but, someone really has to check the modem firmware to see if Intel or Broadcom have included all of the potential 802.11xxx modes of operation. We've seen enough idiosyncrasies in modems that I wouldn't necessarily blame the user device right away. One would need a data capture between the device and modem to really see what's going on and maybe learn enough that blame is placed on the correct device.
@Datalink Recently, some users noticed that their entire WiFi networks went down whenever they turned their laptops on, and it's often a new laptop that they just purchased. Even their Ignite set-top boxes lost connectivity. The most likely trigger is a hardware/driver issue on the WiFi client, but it also indicates that the XB6 gateway is not handling some error conditions properly. (If the XB6 gateway crashes, there might even be an underlying exploitable security vulnerability.)
I wonder if those laptops are 802.11ax capable, which would be reported to the modem or router? Makes me wonder if 802.11ax is listed in the modes that are coded in the modems firmware? It would be worth asking the question of what's the exact laptop model and the exact wifi adapter as seen in the Control Panel .... Device Manager .... Network adapter line. Here's an example off of an ethernet adapter on a desktop:
Atheros AR8121/AR8113/AR8114 PCI-E Ethernet Controller
With that type of information, we should be able to look up the adapter specs to see exactly what it's capable of.
I was running into this exact issue on my mothers laptop.
Unfortunately it fixed itself it seems, so I don't really have a solution.
It was doing the same thing, where as soon as the laptop came on, seemed to kill the wifi on the modem for a few mins, then it would be able to connect.. and often had to re connect the TV boxes as well.
It was a few days before I was able to get to my mothers to actually take a look at it.
By the time I had got there, Her machine was her machine on startup was coming up from a windows update.
When I was there, and since, it has been able to start up every time OK.
So not sure, if it was the windows update which fixed it.
Or if there was a firmware update, etc on the modem at that time, etc.
I wonder if those laptops are 802.11ax capable, which would be reported to the modem or router?
It could be (and I also suspect that this is the case) but it does not necessarily have to be. For example, a few years ago, vendors rushed out fixes to address the KRACK vulnerability, and some of the WiFi client updates did not play well at all with some network gear. WiFi client bugs need to be fixed... but the software on router/gateway/access point also needs to be robust and must be able to deal with any unexpected situations without crashing/failing/locking up/resetting.