Hello @eendejan ,

Welcome to our community.

Besides updating the firmware, have you changed any other settings? Or added any devices to the network?

For an unstable connection, please try the suggestions below:

1) Connect a PC directly to your modem to verify if your ISP's Internet is stable.

2) Ensure the Ethernet cable connecting your modem to the Router is properly connected, and replace old wires with new ones.

3) Please change the DNS Server of the Router, log in to the web management interface of the Router, go to Advanced > Network > Internet > Advanced Settings, and change the two DNS Servers to 8.8.8.8 and 8.8.4.4,  How to Change the DNS servers on the wireless router and DSL modem router (New UI)?

If the suggestions don't help, we recommend sending an email to forumsupport.usa@tp-link.com  with the following information:

Subject: [Forum Escalation][ID 851982] unstable network on Archer AX11000-V1.6 after firmware update.

Forum Nickname: eendejan

Thread URL: ​​​​​​​https://community.tp-link.com/us/home/forum/topic/851982

Model&Version: Archer AX11000-v1.6

Description: 

Once sent, a ticket will be created in our support system, and a member of the team will follow up to gather more information or troubleshoot the case.