Está faltando algum } aqui?
This missing close some } here?
//COMANDOS WEB
EthernetClient client = server.available();
if (client) {
boolean currentLineIsBlank = true;
String str;
while (client.connected()) {
if (client.available()) {
char c = client.read();
str.concat(c);}
if(str.endsWith("/1on"))
{BOTAO1_RELE =1;}
else if(str.endsWith("/1off"))
{BOTAO1_RELE =0;}
if (c == '\n' && currentLineIsBlank) {
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println();
}