First, connections through cables should always be faster than WiFi. If that isn't the case, something is wrong with the cable.
3 ports are occupied with 4-way switches, you say. Given their small size, I assume these are not 'managed' switches. Did you try the 4-way switch with the troublesome device on a different port? If not, swap the device to a different port and see if the problem still exists. Some ports on switches wear out faster than other ones.
There is also this to consider: likely your 4-way switch has 1GByte/sec ports. That means your switch has a total bandwidth capacity of 4GByte/sec when it was new. The quality of the chips used to get to 4GByte/sec bandwidth can deteriorate. After all, it is electronics and not every device is exactly the same.
I have found out that consumer grade WiFi gear and switches vary a lot here in Paraguay. Never liked WiFi as a solution when I still was living in the Netherlands, but here in PY i have learned to hate WiFi with a passion. Even the wired consumer gear isn't always performing as expected. So, I stepped up and spent more on one 'managed' switch with enough ports for now and future needs. It's a Zyxel and I am very satisfied with it.
Reducing the amount of "hops" any LAN or WAN network is always better. Getting one good switch and pulling a cable to a location where you need to use WiFi gear is much more reliable, especially if you stop using consumer grade gear. The max length of a Cat5e/Cat6 cables is 100 meters (after that you need to hook up a switch and from that point you can "travel" another 100 meters, etc.).
I imagine your setup to be like this:
Internet
|
+---------+
| Modem |
+---------+
|
+---------+
| Switch |
+---------+
| | | |
| | |
| | +-----------------------------+
| +----------------+ |
| | |
+---------+ +---------+ +---------+
| Switch | | Switch | | Switch |
+---------+ +---------+ +---------+
| | | | | | | | | | | |
I would suggest the following:
Internet
|
+---------+
| Modem |
+---------+
|
+------------------------------------------------+
| Switch |
+------------------------------------------------+
| | | | | | | | | | | | | | | | | | | |
| | | |
| | | +-----------------------------------------+
| | +-----------------------------+ |
| +----------------+ | |
| | | |
+---------+ +---------+ +---------+ +---------+
| Device | | WiFi 1 | | WiFi 2 | | Device | etc.
+---------+ +---------+ +---------+ +---------+
While this results in a bunch of cables going from the switch into different directions, it may not be the most visual pleasing solution. But it is much more reliable and when I am watching a monitor that is usually where all my attention is focused on. Could be because I am a male
