Series X Keeps randomly disconecting for a sec from xbox network

Hello good morning, welcome to the Xbox community, my name is Fernando and it's a pleasure to help

Fixing the Xbox Ethernet connection issue is not difficult, but we recommend that you perform the following preliminary checks first:

Try disconnecting and reconnecting your Xbox to the Ethernet network.
Make sure your wireless connection is not active as this can tamper with and break your wired connection.
Make sure the Ethernet port on both the modem and the Xbox is not damaged. This can cause the cable to not be properly connected.
Try to limit the number of devices connected to the Ethernet network.
Power cycle your router or modem. So, hold the power button on your router for about 10 seconds and wait until the notification light goes off. Disconnect the Ethernet cable connected to the router and disconnect the router from its power supply and wait a few seconds to allow it to shut down. Connect the necessary cables to your router and connect them to a power source, then press the power button to switch it on .
Try to check if the Ethernet still keeps disconnecting from the Xbox. If so, proceed to the solutions below: Disable Instant-On
Press the Xbox button on your controller to bring up the guide menu.
Browse and select the Profile and System option and click on Settings. Go to General and click on Power and Startup.
Expand Power Mode and select Power Saver and confirm changes. Instant-on mode is quite useful, especially for speeding up the boot process. However, it can also affect the connection after a long period of background activity.

2. Restart your Xbox console
Press the Xbox button on your controller to bring up the guide menu.
Browse and select the Profile and System option and click on Settings. Go to General and click Power & Startup Mode. Select Restart Now from the Power Options. Then select Restart Console. Hope I helped, see you soon!

Done this already countless times. but thanks

But thank you for contacting me, have a great day.

Unfortunately in this case it was the best choice I found, I'm sorry for not having solved your case.

I have the same exact problem - just started randomly happening about 3 months ago. Randomly when I power my Series X off it will disconnect from the known router address and I have to keep setting up a network over and over upon launching it the next time. Then it will be fine for a few weeks and out of the blue rinse and repeat.