It looks like there is a lot of variation in the measured speeds in your case. Some measurements match your typical speed or even higher, e.g. 34.9 MB/s down-speed (that's 279.2 megabit) and 5.75 MB/s up-speed (that's 46 megabit). However a few other measurements are lower, and there are increased ping times when that happens.
There could be a number of reasons: the WiFi itself, some interference, packet loss, or line congestion, which is common for connections like hybrid fiber-coaxial. When you select the router in NetWorx settings, it does not mean speed testing is done from there. It means NetWorx will be polling your router's usage, but speed testing is still done from your computer.
If you want to narrow the issue down, you could run two continuous ping commands in a command prompt and observe their output:
ping 192.168.0.1 (replace this with your router's IP address)
ping 1.1.1.1 (this is a public IP address)
Let them run for a while and see how and if the response times are changing. If both vary a lot, the culprit is likely to be your WiFi. If only the public IP address ping varies a lot, there may be an issue with your connection. Here is a sample of the output: