I'm wondering if this is related link will try the fix tomorrow
Edit: This made no difference - reading Abnormally high latency of wifi with VLANs and Ath11k possible firmware bug - traffic interruptions when a client disconnects from WLAN - #38 by asvio seems this is an issue that no one has really gotten to the bottom of. For now the workaround is to only have one SSID on the 5Ghz adapter