Mobile preferred calls drop

[Avalon100]

Hi
We have a customer on IP500 V9.1 with One X portal and they have an issue where when a user logs using their mobile preferred app (Android or Apple) with One x the connection will drop after 1 minute. The connection will then establish again and drop after one minute, if you are making a call it connects fine and you can talk but again will drop after 1 minute. Anyone see this before or got any ideas?

Thanks

 

[holdmusic34]

If using a wifi service with a few APs in the same network, turn gratuitous arp off.

Sip alg on the router? Turn it off.

Draytek?

this time you gave me a mountain

 

[Avalon100]

SIP ALG is turned off, and this is when connected via 4G