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ER605 static IP assignment - cache or other issue?

ER605 static IP assignment - cache or other issue?

ER605 static IP assignment - cache or other issue?

2025-07-14 13:12:01

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Registered: 2022-10-26

ER605 static IP assignment - cache or other issue?

2025-07-14 13:12:01

Model: ER605 (TL-R605)

Hardware Version: V2

Firmware Version: 2.2.5 Build 20240522 Rel. 75860

I have this issue with ER605: https://community.tp-link.com/en/home/forum/topic/674996?replyId=1468532

Somehow it seems ER605 is keeping some historical information, whatever it may be called (cache?), about static IP assignment. In the issue above I kept having issues with one Deco XE75 Pro unit not being able to retrieve NTP time. I assigned static IP address to that Deco that used to belong to old WDR3600 router which is no longer on the network, not even turned on. As soon as I changed the static IP address for the Deco with issues to something that was never used before, all issues went away.

Now it makes me think - what in the world is going on with ER605 and static IP assignment that is causing this issue? Is there some sort of cache somewhere that is creating this issue? If there is some "cache", how can I clear it? I have a feeling that some of the issues I have on the network would all go away by clearing whatever "cache" or "history" there is on the ER605.

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#1

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2025-07-15 00:55:13

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Re:ER605 static IP assignment - cache or other issue?

2025-07-15 00:55:13

Static IP and cache? I can't really relate them together. Not from what I know about the network.

Or you mean ARP cache? But that should not be a problem for the static IP assigned, AKA DHCP reservation.

I am not sure who told you about the cache thing. Any more explanation or definition about the "cache"?

You probably configured a DHCP reservation, and that MAC address does not match the new device's MAC address. If that's the case, delete the old entry and create the new one with the proper parameters.

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#2

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2025-07-15 07:44:49

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Registered: 2022-10-26

Re:ER605 static IP assignment - cache or other issue?

2025-07-15 07:44:49

@Clive_A Nobody told me about "cache", that is just me trying to understand how ER605 works, does it save information about each IP address and MAC address pair? I have no clue, I am trying to understand why IP address would make any difference on behaviour of Deco unit. Only common thing between previous network where I had only ER605 and WDR3600 and new network with ER605 and now 5 Deco units is ER605. I have removed power to entire network many times since last time WDR3600 was on the network with the same IP address as the Deco that had issues.

In the previous network I assigned static IP address on WDR3600 itself and not on ER605. Does ER605 save some information related to that IP address, like which MAC address was assigned to that IP address and when a different MAC address is assigned the same IP address now the ER605 creates routing issues?

I am willing to test. Right now all Decos are working fine. I can take one Deco, any Deco XE75 Pro and give it that old IP address that WDR3600 had. If the same issues occur with any (or all Decos) then it has to do with ER605. Actually, I will do the test anyway and provide results here. I expect each Deco that gets assigned that IP address will have issues.

Can you please tell me then does ER605 save some information related to each MAC address/IP address pair and by some bug it does not delete that information and that causes issues?

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#3