@Sunshine I've now purchased a TP-Link Deco X50-4G, which seems to suffer from the same problem. The TP-Link app on my phone typically reports the network as "4G" but occasionally switches to "4G+"....

Has anyone tried the latest firmware for v3 of the MR600 (Archer MR600(EU)_V3_220727, dated 2024-01-22)? The release notes don't mention this specific issue, but I'm wondering if it was quietly fixed...