Hello all, I've been trying to do lots of reading on the issue I'm having and cannot figure it out.

Due to Covid my wife has been working from home and because of this she is using a work laptop. After returning from deployment overseas I came home to a horrible slow network, I originally thought it was her hogging all the bandwidth on our 300Mbps connection (typically got 350 before I left) so I moved to a Gig plan and was only getting max 650-700, I talked with my ISP and they said that was perfect for my plan. Well I kept having a slow connection on all my devices when my wife (connected by Wifi) was connected so I bought a switch with QoS and hardwired her, I still kept having issues. So the ISP tech came by and I showed him that when she was on during the day the connection would max out at 20Mbps and even with her being disconnected speeds would not increase unless we restarted the modem. He talked to the service department and they told him I was not being throttled at all and I wasn't close to their threshold to start throttling.

The issue we both figured was it was a bad modem (Arris XB6 has the Intel Puma issue) so he replaced it with a Technicolor XB6 (which has a Broadcom chipset and supposedly better in every way). After this I was hitting 700Mbps which was better but once my wife connected to it the next day the speeds would slow to a crawl and even fully disconnecting her the speeds won't increase without a full restart of the modem.

Does anybody have an idea what the issue could be? I'm going nuts trying to fix this issue and constantly having to fully restart the modem every day is killing us.

I was thinking of buying my own modem (not a XB6 or Puma plagged model) but my ISP told me I cannot use a third-party modem.

FYI: - Everything we have has a 1G capable connection or higher (10G on switch and my computer). All devices wired using Cat7. - A few neighbors have the same plan and ISP but are getting ~900Mbps speeds.

Thanks in advance!