I did some testing today and found that (at least on my device) the wifi instability with S6 blobs might be because they're not coping with a dual-band network (2.4GHz and 5GHz bands in the same SSID).
I found S6 blobs choose the 5GHz band, don't switch to 2.4 GHz if the 5GHz signal quality is poor or missing, and don't always automatically reconnect to 5GHz when the signal improves. S2 blobs also prefer the 5GHz network, but don't drop out as quickly if its signal quality is poor, and can switch to 2.4GHz if the 5GHz signal is low or missing.
I also found that both S6 and S2 blobs are quite stable if the network is single-band, whether that is 2.4 or 5. Both of them reliably reconnect automatically on reboot to a single-band network, and stay connected.
Have other people who've had problems with unstable wifi also been using dual-band networks?