Well, we can’t really answer this question unles you tell us the manufacturer and model number of the router.

However, I suspect that the answer is to set the lease time to 0 (zero).

@the100thmonkey The manufacturer and model number is Strabridge Linx 525.

@the100thmonkey is correct about setting this parameter to zero.

@Dr_Lawrence @the100thmonkey I tried setting it to 0(zero) but it says that” the parameter 0(zero) is out of range of [1–65535]” so, do I need to set it to 65535 instead? Because my leased time I have to set it in hour

The 65535 hours will give you approx 7.5 yrs before you need to worry about it again. Unless you are luckier than I am, you’ll be replacing it before then. So, yes, set it for the 65535.