1. The cost of broadband is insufficient. Right now, broadband is basically a postpaid model. Because of the long delays, the operators simply shut down the broadband. In this case, you need to pay the arrears to recover;
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2. The optical signal interface of the router is faulty. The connection port may be loose or poor contact. In this case, you need to remove the optical signal crystal connector and reinsert it.
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3. The router is broken. This kind of thing rarely happens. When the router is damaged, only the optical signal does not flash red, so try restarting the router.
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4, the upper connection splitter failure, generally in this case, the surrounding neighbors can not access the Internet. This can only be reported to the operator and other staff on-site repair