@brent Well, because signal strength doesn't seem to be the problem (and certainly won't be after you've moved the modem/router) let's come up with a plan to deal with other possible problems.
Congestion
@Axios said (in the comment immediately above and in earlier comments) the symptoms you are experiencing are consistent with signal congestion, and I agree that congestion is a likely culprit once poor signal has been eliminated.
Signal strength will be eliminated when the modem/router is moved to the area where you and your partner use your respective computers, so the next step is to look at congestion. To look at congestion, we will need to see what signals are broadcast by other modem/routers and wifi routers that are close enough to be picked up by the laptop. After you have installed WiFi Analyzer (it would be best to install it on the laptop from the Microsoft Store, but you could also install it on your smartphone, assuming that it is an Android phone), you will be able to build a congestion map like the one showing my wifi environment above.
I don't know what we will find, but looking at the congestion map for my wifi environment (see above), you can see that the 2.4 GHz channels 6 and 11 are very congested, but 2.4 GHz channel 1 is relatively uncongested. If I were using 2.4 GHz, I would switch the modem/router to use Channel 1, and that would reduce congestion issues. Depending on the age of your partner's laptop (in general, laptops built within the last 5-6 years using Intel adapters work with both 2.4 GHz and 5 GHz) and the capabilities of the laptop's wifi adapter, you might also be able to switch over to 5 GHz. That's what I did, because in my case the 5 GHz bands are uncongested.
So, as the next step, install WiFi Analyzer and let's see what the picture looks like. We might find the answer there.
As background for this part of the inquiry, it would be helpful if you would provide us with:
(1) The make and model of your partner's laptop. That will allow us to figure out what wifi adapter the laptop uses, which in turn will allow us to find out of the adapter supports both 2.4 GHz and 5 GHz bands.
(2) The make and model of the CenturyLink modem/router. This will allow us to find the appropriate menus needed to make changes to the channels being used by the modem/router. Based on your description of the "cone modem", my guess is that you have a C4000 modem, but we should confirm.
Other Possible Problems
We'll have to see what develops, but I can think of two additional problem areas that we might need to explore if moving the modem/router and/or resolving congestion issues don't resolve the problem.
The first is a settings mismatch between the modem/router and the laptop's wifi adapter. Windows 10 and modern modem/routers are good at negotiating resolving protocol mismatches, but we might need to look into this potential issue.
The second is interference with wifi adapter operation because of the way in which your partner's laptop is configured, using a docking station as it does. I've not seen the issue on my laptop with a docking station, but I have experienced other issues, where the docking station turns various things on/off in ways that I would not expect. It is not a likely source the problem, but if nothing else works, we will need to take a look.
