diff --git a/drivers/modem/modem_cellular.c b/drivers/modem/modem_cellular.c
index affc72f70fb..564afaafecf 100644
--- a/drivers/modem/modem_cellular.c
+++ b/drivers/modem/modem_cellular.c
@@ -1924,7 +1924,7 @@ MODEM_CHAT_SCRIPT_CMDS_DEFINE(swir_hl7800_init_chat_script_cmds,
 			      MODEM_CHAT_SCRIPT_CMD_RESP("", ok_match),
 			      MODEM_CHAT_SCRIPT_CMD_RESP("AT+CIMI", cimi_match),
 			      MODEM_CHAT_SCRIPT_CMD_RESP("", ok_match),
-			      MODEM_CHAT_SCRIPT_CMD_RESP_NONE("AT+CMUX=0,0,5,127", 0));
+			      MODEM_CHAT_SCRIPT_CMD_RESP("AT+CMUX=0,0,5,127", ok_match));
 
 MODEM_CHAT_SCRIPT_DEFINE(swir_hl7800_init_chat_script, swir_hl7800_init_chat_script_cmds,
 			 abort_matches, modem_cellular_chat_callback_handler, 10);
diff --git a/samples/net/cellular_modem/boards/mg100.conf b/samples/net/cellular_modem/boards/mg100.conf
index c19245d045f..3b6ae6e7d57 100644
--- a/samples/net/cellular_modem/boards/mg100.conf
+++ b/samples/net/cellular_modem/boards/mg100.conf
@@ -1,2 +1,3 @@
 CONFIG_MODEM_HL7800=n
-CONFIG_UART_ASYNC_API=y
+CONFIG_MODEM_CELLULAR_CMUX_MAX_FRAME_SIZE=255
+CONFIG_NET_BUF_TX_COUNT=32
diff --git a/samples/net/cellular_modem/boards/pinnacle_100_dvk.conf b/samples/net/cellular_modem/boards/pinnacle_100_dvk.conf
index c19245d045f..3b6ae6e7d57 100644
--- a/samples/net/cellular_modem/boards/pinnacle_100_dvk.conf
+++ b/samples/net/cellular_modem/boards/pinnacle_100_dvk.conf
@@ -1,2 +1,3 @@
 CONFIG_MODEM_HL7800=n
-CONFIG_UART_ASYNC_API=y
+CONFIG_MODEM_CELLULAR_CMUX_MAX_FRAME_SIZE=255
+CONFIG_NET_BUF_TX_COUNT=32