iOS app 'Connection Lost, reconnecting'

Tags: #<Tag:0x00007f7399592dd8>

Often when we (husband and I) open our iOS apps, the app will show ‘Connection lost, reconnecting’ for up to 5 minutes. At the same time home kit devices show as unavailable (not sure if this is related).

We have a pretty basic setup - this happens both when connected to our home wifi and 4G
iPhone 11 and XR with latest iOS version, latest iOS Home assistant app
Home Assistant Core 0.113.2
Raspberry Pi 3+ with HassOS 4.11
DuckDNS and DNSMasq Addons.
Ubiquity Dream Machine router with static IP set for Raspberry pi and forwarding port 8123.

Not too sure where to start with this - there is an error showing in the core log around the time the app is having trouble connecting.

2020-07-31 15:30:24 ERROR (MainThread) [frontend.js.latest.202007021] https://xxxxxx.duckdns.org:8123/frontend_latest/chunk.b33c9e401dd2387e7c3f.js:2:20586 TypeError: undefined is not an object (evaluating 't._leaflet_pos')
2020-07-31 15:30:25 ERROR (MainThread) [frontend.js.latest.202007021] https://xxxxxx.duckdns.org:8123/frontend_latest/chunk.b33c9e401dd2387e7c3f.js:2:20586 TypeError: undefined is not an object (evaluating 't._leaflet_pos')

have removed and re connected the app to HA, now it connets and logs in but it will not add any sensors ?