s9 call problems after update

[shortie2]

cant make or receive calls after update , immediatly disconnects after call is answered ,send or receive , initially thought it was sim card related and fitted new sim , it worked for 1 call then resorted back , tried carrier reset and full factory reset with no joy

[shortie2]

ok so it turns out the update sets the network to 4 g only , set it back to 3g and now ok