lwip: ping不通

能ping通时打印信息：

tcpip_thread: PACKET 0x200122d8
ethernet_input: dest:0hx:0hx:0hx:0hx:0hx:0hx, src:0hx:0hx:0hx:0hx:0hx:0hx, type:0
ip_input: iphdr->dest 0xc401a8c0 netif->ip_addr 0xc401a8c0 (0x1a8c0, 0x1a8c0, 0xc4000000)
ip4_input: packet accepted on interface st
ip4_input: 
IP header:
+-------------------------------+
| 4 | 5 |  0x00 |        60     | (v, hl, tos, len)
+-------------------------------+
|    57141      |000|       0   | (id, flags, offset)
+-------------------------------+
|  128  |    1  |    0xd710     | (ttl, proto, chksum)
+-------------------------------+
|  192  |  168  |    1  |  102  | (src)
+-------------------------------+
|  192  |  168  |    1  |  196  | (dest)
+-------------------------------+
ip4_input: p->len 60 p->tot_len 60
ip4_output_if: st0
IP header:
+-------------------------------+
| 4 | 5 |  0x00 |        60     | (v, hl, tos, len)
+-------------------------------+
|    57141      |000|       0   | (id, flags, offset)
+-------------------------------+
|  255  |    1  |    0x0000     | (ttl, proto, chksum)
+-------------------------------+
|  192  |  168  |    1  |  196  | (src)
+-------------------------------+
|  192  |  168  |    1  |  102  | (dest)
+-------------------------------+
ip4_output_if: call netif->output()

ping不通时的打印信息：

tcpip_thread: PACKET 0x200122d8
ethernet_input: dest:0hx:0hx:0hx:0hx:0hx:0hx, src:0hx:0hx:0hx:0hx:0hx:0hx, type:ff
etharp_update_arp_entry: 192.168.1.102 - 90:78:41:d1:13:84
etharp_find_entry: found matching entry 1
etharp_update_arp_entry: updating stable entry 1
etharp_input: incoming ARP request
etharp_raw: sending raw ARP packet.
ethernet_output: sending packet 0x200122f0

经测试发现，问题出在：整套代码基于STM32F407VGT6开发的，然后直接下载到GD32F407VGT6中才出现上述问题。GD32F407VGT6中也只是偶尔会出现此类问题，不是每次都出现。STM32F407VGT6测试50次，一次都没有出现问题过。