Like IraHall posted on 6th Feb this year as "1-3 second delay on most inbound calls" i have something similar.
A: Large house (9 extensions 3 x Fanvil X6uV2 & 6 x Fanvil W611W) Internet comes in here > Draytek Router > Switch
B: small office (2 x Fanvil X6uv2)
A&B are connected via Cat6Ethernet cable link with PoE switches at either end, there are also Unifi WAPS in both A & B.
They had similar issues last year and these where resolved by installing a Raspberry Pi as SBC and telling all the phones to use that as SBC instead of the Fanvil phones as router phones, and all problems went away - now they are back.
Tried to bypass the SBC making 1 phone its own Router phone and this, if anything, was worse!
The thing i don't get is why the APP works on Mobile and the Fanvil Phones suffer (Main call handler has desk phone and app on mobile, when the problem started they switched to using phone app by default). The app user in the office is connected to a WAP in the office, and this, just like their phone, connects to the switch in the office, and goes over same ethernet cable to house switch> Router> Internet> 3cx Hosted 4sc pro.
I've been there this morning and internet is fine, tested from both locations it is FTTP only 100mb but low latency 8-10ms. Switched everything off and back on again, and all seemed fine after that - until i left! Now that seems like a loop error dragging the network down to me (even though i am sure there are no loopbacks). So I've ordered new switches, but if its the switches/s why does the Wi-Fi App user in office not suffer like the physical phones?
Before i left, I started the call monitoring on main callers phone, looking at them, it was a mixed bunch, with worst having a 7.5 seconds roundtrip! I rung them to say i can see its still bad, but sometimes o.K and they said after it went bad they only answered on app, I asked for next call i make to them to answer on telephone handset, I called in on landline and saw all the phones flashing red status (only 2 should have been ringing) and eventually a different extensions answered. when I called app to app to main call handler they said they tried to answer call on desk phone but it wouldn't answer, the app to app call was fine.
My plan is to change the switches and maybe also the Pi as well - though it seems fine and reports no errors.
As ever I'm writing it down then posting, as much to get it straight in my head, and moreover in the hope someone's outside perspective will focus on something I'm not looking at or considering...
Thanks
