@Giorno_Giovanna Hi, welcome to the community. May I know your SIM carrier? A new firmware 1.3.0 was released a few days ago. It is recommended to update to the latest firmware version to see whether...

@Flo2010 Hi, welcome to the community. Did it help to enable QOS and manually set the bandwidth to be 2Gbps download and upload when the 2.5G port is connected to the ISP modem? Wait for your reply....

@ByTP Hi, thank you very much for the message. Could you please refer to this link to help me submit the Deco App log here: How to submit Deco APP log The firmware 1.2.0 can't be downgraded back to...

@LeZs Hi, thank you very much for the update. Did you receive my email? I didn't have any other suggestions, and the case has been escalated to the senior engineer for further assistance. It is...

Update: Please refer to the reply here: https://community.tp-link.com/en/home/forum/topic/824136 Best regards.

@Sebcbien31 Thanks for the update. If you still had this issue, could you please help me submit the Deco APP log? Wait for your reply. Best regards.