wifi connection keeps being dropped: 18.04 on Lenovo IdeaPad

[No Nickname]

Xubuntu 18.04 installed on a new Lenovo IdeaPad 330S; system is up to date (I run Software Updater pretty much daily).
lsb_release -rd tells me:
Description: Ubuntu 18.04.3 LTS
Release: 18.04

I am connected to the internet via a wireless router and although the desktop panel network icon tells me I am always connected to the router, every so often the actual internet connection stops working -- as in, I am connected to the router, but websites won't load or Firefox will say I am offline.

If I click the network icon on the desktop panel and uncheck and then re-check "Enable Networking", the computer reconnects to the router and the internet connection works again, at least for a while.

I cannot discern any specific pattern to this behaviour; it seems to happen randomly -- but often enough to be really disruptive.

Other devices connected to the same router (two Android phones and an older laptop running Linux Mint) do not have this problem.

EDIT: Even when I do stay connected, the connected speed is often ridiculously slow, at 1 Mb/s -- as opposed to e.g. 144 Mb/s on another device connected to the same router. Restarting the network as above seems to solve the issue for a short while -- although I'm not sure, since clicking on "Connection Information" then lists "Speed" as "Unknown". After a while it then goes back to "1 Mb/s".

My apologies if I didn't report this correctly or left out anything important; I am just an end user and not an expert. Please let me know if I need to provide any further information.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1840931/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[No Nickname (nonickname2)]

Ok, so I specified "network-manager" as the package. Don't know if that's correct, though.

[Kai-Heng Feng (kaihengfeng)]

What's the wireless card does the system use?

[No Nickname (nonickname2)]

I hope this is the information you need (I followed these instructions: https://itsfoss.com/find-network-adapter-ubuntu-linux/):

Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31)