Hopefully, this post will not be as dense as my last ones.
I have been running openwrt 21.02.0 in a vbox VM, and it has been very reliable. However, after upgrading it to 21.02.1, and installing the packages my configuration requires (hostapd and a usb NIC driver unrelated to the wireless), the access point is unreliable -- my laptop will not stay connected. It disconnects after a short time, or if I try to do any network activity. I (cold) rebooted both the openwrt router and the laptop several times, but it made no difference. Interestingly, my smart phone stayed connected -- most of the time, far more than the laptop.
I was using hostapd as the AP, but I tried switching to wpad, which I've used in the past with success (iirc). Anyway, wpad did not work at all. (Did I need to reset the whole configuration and set it up from scratch? If so, my apologies in advance; I was hoping to not need to do that.)
In the interests of being able to use my laptop, I reverted to a snapshot just before I performed the upgrade; that is, back to 21.02.0, and it seems to be working again as before, without any reboots or tweaking. My laptop stays connected with the AP without any problem, as does my phone.
The laptop is an ASUS T101AH which has a built-in wireless adapter Qualcomm QCA9377. Tbh, I have had some issues with this machine and regret having bought it; I was lured by the price mainly. One problem I can recall, where wireless would stop, was resolved by disabling the powersaver. The laptop has been running devuan beowulf for several months without any real issues I can recall. The wireless problem began today after attempting the upgrade to 21.02.1.
The openwrt logs have endless messages that look like:
rtlwifi: -----hwsec_cam_bitmap: 0x0 entry_idx=4
I am seeing these messages in both 21.02.0 and 21.02.1, and I've seen them in previous versions. Other than these, I don't see any repeated messages that might be errors. I searched the web for info on this, but there are no recent hits (ddg and google) other than some developer emails about this, but little that indicates a resolution (that is, apart from patches, etc). The only differentiating thing I notice is that these messages were extremely prolific with 21.02.1, whereas I only get a few on 21.02.0. I am not sure if this has anything to with this particular problem, but included it for completeness.
The AP is a Belkin wireless N USB and I haven't had any serious issues with it. It was the first usb wireless I bought, and I've had it for about 8 years I think. I have been using it with openwrt since I started using openwrt around 19.07.5(?).