diff --git a/rtl837x_init.c b/rtl837x_init.c
index 73498642..cc2adfcd 100644
--- a/rtl837x_init.c
+++ b/rtl837x_init.c
@@ -221,9 +221,11 @@ void rtl8372_init(void) __banked
 	} else if(machine.n_10g == 2) {
 		REG_SET(RTL837X_REG_SDS_MODES, 0x1ad); // Both 10g ports use SDS_QXGMII
 	} else {
+		// Replace the reset value 0xbff (both SDS off) instead of ORing into it:
+		// RTL837X_REG_SEC_COUNTER only holds a written value while SDS 0 is on
 		reg_read_m(RTL837X_REG_SDS_MODES);
-		sfr_mask_data(1, 0, 0x03);
-		sfr_mask_data(0, 0, 0xe2);
+		sfr_mask_data(1, 0xff, 0x03);
+		sfr_mask_data(0, 0xff, 0xe2);
 		reg_write_m(RTL837X_REG_SDS_MODES);
 	}