Put some tape over them.

Also the wired device may not have a gigabyte ethernet. Its max may be only 100.

Check the guest controls as that may work for you.

You may be getting interference from some other wireless device or from someone else WIFI. Other devices may be interfering with the radio signal. Things like cordless phones, wireless security...

Sounds like you added another device in series which is not always a good thing. Is the W1043 hardwired? Why two routers? Can you replace the W1043 with the Archer?

Get the modem/ISP issue resolved? Once resolved, then see if you still have the WIFI/connected issue.