@Tiptironical Hello,
If only 5Ghz got unstable issue, please login web page and change 5Ghz Channel width to 80Mhz to reduce possible interference.
Changing Channel and Channel Width on AC VDSL or ADSL Modem Router (new logo)?
Please try a different Wi-Fi channel on 5Ghz, 36/40/44/46 is recommended , please avoid DFS channels motioned the FAQ below:
https://www.tp-link.com/support/faq/763/
Also confirm your VR300 is on the latest firmwar
: https://www.tp-link.com/support/download/archer-vr300/#Firmware
If the same issue, may I know did 5G work fine before, is there any Error message on 5Ghz wifi or 5Ghz WIFI is still connected but no Internet access?
Is there any video stream, file downloading or large traffic network actives when this issue happens, what are the devices connected to 5Ghz and get unstable problem?
Thank you in advance