iOS calling drops (380.68_4)

[Nigel Jones]

I have a RT-AC3200 using merlin 380.68_4. Amongst a myriad of devices I have an IOS device (11.1, now 11.2 beta) with wifi calling (Vodafone UK). I get call drops at home, but wifi calling seems ok elsewhere. I may lose the call within a minute, or several minutes, but it will be pretty quick.

After a little experimenting I think I only suffer these drops in my dining room, one floor down, one room across (brick, 3 storey) from the router. Near the router I've made successful 1hr wifi calling calls. That being said other devices seem to work fine, and I don't notice connectivity issues on the iPhone.

My guess is that perhaps the iPhone 7+ is roaming between 2.4 and 5 Ghz, or between 5-1 and 5-2 ... use of 'smart connect' for example.

Does this sound a feasible hypothesis? Any other thoughts?
one might argue a momentary blip shouldn't break a wifi call (native iOS - SIP calls using 3rd party apps don't seem to be affected(

What I've done so far
- disabled airtime fairness across all bands
- turned off universal beamforming
- roaming assistant is already off

To test this theory my next plan is to switch off smart connect, though it could be the signal level in that area is still borderline 2.4 -> 5.

Intrigued if anyone else might have seen wifi calling issues, especially with iOS

Nothing to suggest this is merlin specific but figured as I'm using the fw I should start here?

 

[JDB]

Mine is rock solid on the same f/w (albeit with EE - but the mechanism is identical from the routers point of view regardless of carrier).
It is sensitive to Wi-fi band shifts though. I have to be careful not to hover too long at the far end of my kitchen when on a call (swift entry to the biscuit cupboard only!) else it’ll go to 2.4ghz and it does seem to drop a call some of the time if it does.
It’s not a straight up VoIP call though, it’s over a VPN tunnel and within that it’s using IMS compliant SIP, so it is checking regularly for an acceptable IP connection to support the call. Idea being it would switch you back over to VoLTE if the Wi-fi was no longer good enough (however not all carriers support/allow call handover from Wi-fi to VoLTE), or like me you may not have 4G/LTE reception at home so handover is not possible (the iPhone doesn’t allow handover to 2/3G from Wi-fi).

I’d guess it is Wi-fi Channel hopping that does it.


Sent from my iPhone using Tapatalk

 

[Nigel Jones]

A few experiments
* with smart connect off I still got a drop quickly
* I also get a drop if I intentionally walk away from the router (outside) with the phone on 5Ghz .. somewhere 2.4 should be fine - the implementation seems awfully sensitive
* A roam 2.4->5 seems seamless though this isn't forced by smart connect, but now a phone decision

Wondering if the iOS implementation is just a bit rubbish tbh...

Reading around some more I can now see lots of examples of roaming (ie with dual band routers, same SSID) causing issues. perhaps I finally have to give in and go for split SSIDs to avoid roaming in-home

So 802.11k, 802.11v may help. Does the AC-3200+merlin support this? Where would I find config?

 

[Nigel Jones]

Thanks for the reply...

I'm with Vodafone, and no VoLTE yet, so there'll be no wifi->volte roaming. Just 3G. coverage is just about ok in the worst part of the house, but I wouldn't normally lose the call. enough for wifi calling to kick in though, and its handy when I go to other places. I could disable entirely, though I'm inclined to do the ssid split. I'm pretty sure now that it is the roaming that causes a drop (yet not 2.4 -> 5), whether initiated by phone or router (ie smart connect)

Yes understand wifi calling isn't just sip, I was just comparing the end user experience which is pretty much zero effect (perhaps a brief stutter) if roaming occurs.

 

[Nigel Jones]

Just doing a SSID split will result in my iPhone 'sticking' on 2.4 Ghz - it picks that up first, and it has the best coverage. Windows PCs are more forgiving I think due to having the concept of network priorities. Not experimented with macOS yet.

So I think the only thing I can do is to
- ditch 1 5 Ghz band (no real value except capacity)
- split SSIDs on 2.4/5
- set clients to only auto connect on 5, leaving 2.4 as a manual backup.

I guess this is why professional managed wifi network equipment exists. Something so simple, yet so hard........