diff --git a/artiq/runtime/liblwip/liteethif.c b/artiq/runtime/liblwip/liteethif.c
index ddc2df9cc..2e57e26b7 100644
--- a/artiq/runtime/liblwip/liteethif.c
+++ b/artiq/runtime/liblwip/liteethif.c
@@ -131,7 +131,7 @@ err_t liteeth_init(struct netif *netif)
     netif->name[1] = IFNAME1;
     netif->output = etharp_output;
     netif->linkoutput = liteeth_low_level_output;
-    netif->mtu = 9000;
+    netif->mtu = 1514;
 
     liteethif->ethaddr = (struct eth_addr *)&(netif->hwaddr[0]);
 
diff --git a/artiq/runtime/liblwip/lwipopts.h b/artiq/runtime/liblwip/lwipopts.h
index 46bd0ca5b..1dc945e96 100644
--- a/artiq/runtime/liblwip/lwipopts.h
+++ b/artiq/runtime/liblwip/lwipopts.h
@@ -94,10 +94,10 @@ a lot of data that needs to be copied, this should be set high. */
 
 /* ---------- Pbuf options ---------- */
 /* PBUF_POOL_SIZE: the number of buffers in the pbuf pool. */
-#define PBUF_POOL_SIZE          384
+#define PBUF_POOL_SIZE          512
 
 /* PBUF_POOL_BUFSIZE: the size of each pbuf in the pbuf pool. */
-#define PBUF_POOL_BUFSIZE       9036
+#define PBUF_POOL_BUFSIZE       1536
 
 /* PBUF_LINK_HLEN: the number of bytes that should be allocated for a
    link level header. */