.config - Linux/arm 4.9.37 Kernel Configuration
     Device Drivers 
         -> [*] USB support
             //4G配置
             --><*> USB Serial Converter support
                 ---><*> USB driver for GSM and CDMA modems
         -> [*] Network device support 
             //wifi
             -->[*] Wireless LAN
                  --->[*] MediaTek devices                                                     
                     ----><M> MediaTek MT7601U (USB) support
                  ---><*> USB ZD1201 based Wireless device support 
             //4G
             --><*> USB Network Adapters
                  ---><*> Multi-purpose USB Networking Framework 
                       ----<*>Host for RNDIS and ActiveSync devices 
             --><*> PPP (point-to-point protocol) support                                             
                 ---><*> PPP BSD-Compress compression                                                       
                 ---><*> PPP Deflate compression                                                            
                 --->[*] PPP filtering                                                                      
                 ---><*> PPP MPPE compression (encryption)                                                  
                 --->[*] PPP multilink support                                                              
                 ---><*> PPP over Ethernet                                                                  
                 ---><*> PPP support for async serial ports                                                 
                 ---><*> PPP support for sync tty ports 
         -> Character devices 
                     //串口
             --> Serial drivers
                ---> <*> ARM AMBA PL011 serial port support                                                   
                ---> [*]   Support for console on AMBA serial port 
[*]  Networking support (优先设置)
       -> Networking options
           --> <*> Packet socket 
           -->[*] TCP/IP networking           
                    //DHCP配置
                   ---> [*] IP: DHCP support                             
                   ---> [*] IP: BOOTP support                            
                   ---> [*] IP: RARP support
       ->-*- Wireless 
           --> <*>   cfg80211 - wireless configuration API 
           --> <*>   Generic IEEE 802.11 Networking Stack (mac80211) 

配置Busybox，使能以下选项:
Networking Utilities
    -> [*] udhcp client for DHCPv6 (udhcpc6)                                
    -> [*] udhcp server (udhcpd)                                         
    -> [*] dhcprelay
    -> [*] udhcp client (udhcpc)                                            
           -->[*] Verify that the offered address is free, using ARP ping (NEW) 
           -->[*] Do not pass malformed host and domain names (NEW)             
           -->[*] Support for RFC3397 domain search (experimental) (NEW)        
           -->[*] Support for 802.1Q VLAN parameters (NEW)