The problem is that you are using too old snapshot, some of the early builds. It also might not be fully compatible with the updated packages.
The current build from today is SNAPSHOT (r25595-5305dbbe9f). I would recommend installing it from Luci.
But before that, read this whole message first!
First do config backup from Luci. Then do backup the list of packages and reinstall them. The easiest way to do it that I know of is this script:
Do the following before doing the sysupgrade (and do it from the terminal):
wget https://raw.githubusercontent.com/richb-hanover/OpenWrtScripts/main/opkgscript.sh
chmod +x opkgscript.sh
./opkgscript.sh -v write
It will save a file with your current packages and it will “survive” the sysupgrade.
Then install latest snapshot for your router from the Firmware Selector:
https://firmware-selector.openwrt.org/
Make sure you selected appropriate options during the upgrade in Luci to keep your config files on the persistent partition.
Pay attention that after upgrading to the latest snapshot, your router will not have Luci installed. So make sure before that you have an access to ssh.
You install Luci with:
opkg update
opkg install luci luci-ssl wget
Then re-download the same opkgscript.sh from above, but this time run this command:
./opkgscript.sh install
It takes a lot of time to finish installing all your packages. A notice here: you always need to run opkg update before that!
Now you have the latest snapshot up and running. I had some issues with accessing Luci on a snapshot from couple of days ago, so if you are experiencing any problems with Lua scripts like I did, just check out a few posts before this one - you will find an easy solution there, and that is reinstalling a few packages.
There’s an alternative to using opkgscript.sh, and that is to manually install packages from your list of packages, so use that one if it’s easier for you.
Now you need to install and set up SQM cake properly. In order to be able to handle 1Gbps internet connection on SQM cake, do not forget to enable packet steering, soft offloading, and do NOT use hardware offloading, since it’s incompatible with SQM. Do not forget to install package “irqbalance” for proper CPU load balancing.
For instructions how to do that, scroll back 100+ posts, or use search option to search this thread for keywords “sqm” and “cake”. There was a long discussion there, with a lot of details. You will learn a lot of new things about making your connection very responsive and hard to lag (no buffer bloat).
Installing latest snapshot and reinstalling packages will take you no more than 10 minutes. You can do it every week or so, since it will take a few minutes only. Setting up SQM will take you a little bit longer than that.
You will now have a rock solid router that is capable of handling wifi 6, 2 x 2.5GbE and gigabit SQM cake. This router is a dream machine that has all the features you need from a router integrated into one small and silent package. 
Timeouts will be a thing of past. Enjoy your router!