VoWifi won't recieve calls after luci-app-wireguard

Installing and Using OpenWrt
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Hello :waving_hand:!
I have an xiaomi ax3200 , i installed openwrt and set it up.
I installed luci-app-wireguard package so to use a wireguard vpn but since then my cell phone stop recieving calls from VoWifi.
I have not set up any vpn yet . When i uninstall this package everything returns to normal and i receive calls .

I have been searching for a day to solve this but i cannot.
Does anyone had a similar problem and solved it ?

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What is likely happening here is that the traffic that comes in via the wan for your phone service is being routed out via the VPN, causing the connection to fail.

You'll need to know some basic information about your phone service -- namely ports and source IPs or domains. This way you can create appropriate policies to ensure that the VoWifi traffic can egress through the regular wan rather than the VPN. That is implemented with policy based routing.

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If you do not use an external phone service but talking about wifi calling then it might be an MTU problem.
Lower the MTU on the WireGuard interface from its default 1420 to 1280, sometimes you even need to go lower.

Also make sure MSS clamping (option mtu_fix) is enabled on the firewall zone the WireGuard interface is in.

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Thanks for answering. I 've been running tcpdump for the past day but i cannot seem to find dropped packets.I also setup PBR found ip and ports that are needed for vowifi but no good results yet .

Update : i am nearly sure it is surfshark's server problem and the only way to solve this might be pbr indeed . But pbr drives traffic to wan and wan drives traffic back to vpn.

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  1. Try creating PBR rules for VoWifi traffic that explicitly use your WAN interface as the gateway
  2. Give those rules higher priority than any rules that might send traffic through the VPN
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Thanks everyone :folded_hands:! I solved it, the answer was before my eyes. I couldn't get the pbr to work firstly due to disabled dhcp in wan settings and secondly kill switch was cutting of wan traffic . As soon i set them up the right way :winking_face_with_tongue: i found what ports vowifi uses and made a policy for them .. Now everything works like a clock! If ot wasn't for all of you i wouldn't have found it!

Thanks again!!

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