Hay I have the same issue I think the problem is in ISP modems in every mode Bridge and Access  Point I have cable modem Hotbox 2 (inside box sagecom modem) in bridge mode Router TP-Link Archer C80 upgraded  and i have the same problem whith DHCPS:lease host name not found and drop connection and lags. And i found in the default settings in tp link MTU 1500 I changed to 1452 (To set MTU parameter you can check dns or ip of your provider online)  and connection started to be more stable there is sometime  the issue with orange light on tp link  but the tp link is  now response faster to receive new ip adress But everyday I have one or two issue with DHCPS:lease host name not found But after Seting the MTU Response of the Tp link is more faster and stable connection I think also that TP link have to upgrade firmware maybe may post help someone Good Luck

@Kevin_Z Hello, I've been having the same issue and it's driving me crazy... the router just crash and i have to shut it down and turn it on again.

For example when i make a videocall it's worst.

Sorry for my english. i'm stil learning.

@ShotGal Hay if you are using cable modem check in bridge mode or access point start from beginning if access point  then you can enter your isp provider  setting configuration, modem and check the connection is here are everything ok like downstream and upstream channel channel if one of 4 channel is missing you have problem with cable connection or splitter outside the house your isp technician have to come and fix it but now because corona they are doing troubles  telling that everything alright. Now i checked with other router  bridge and access point  the same problem  tp link is not  the problem only modem from your provider check also  event log  in modem no in router  i suggest try to change internet provider with modem.

@ShotGal First, sorry for my english...

I discover something... when a device without a hostname (example: DESKTOP-VUMNDK) like a generic android device, connect using DHCP; the router try to get the hostname to the device, but fail (because the device dont have a hostname); THEN mark the log with a "WARNING: DHCPS:lease host name not found" and assign the text "Unknown" in the label CLIENT NAME to identify the device.

For test this: just reboot the router and connect the generic device. Go to "DHCP -> DHCP Client List" to identify the device with the label "Unknown" and take note to the Lease Time. Then subtract the Address Lease Time (setting in DHCP -> DHCP Settings) with the Lease time, to identify the session time and subtract again with the actual time. This give you the same time marked in the log with "DHCPS:lease host name not found"

So... this mark it's not involved with any connectivity fail in the router.

@lleiva 

Now I'm just guessing, but in your DHCP settings the settings for optional default gateway and primary and secondary DNS are all empty? what happens if you point them (at least the first two) to your router? 

I'm getting the same "lease name not found" but I don't really have any issues with it all. With a brand new Archer C8. It "just" looks like lan dns lookup that fails. I'm testing my idea, and will let you know what I find.

The same issue is happening with Archer C24.

TP Link doesn't care about after sale service :)

@Calvin_K 

I've had the same issue.

Solution: IP/MAC Binding was activated (Security settings) and this did not work well with my Android clients.

Please check if you have this binding activated or not.

Another idea: Have you configured a static IP for a dedicated MAC address?

Other info: I have deactivated DHCP on the ISP router in advance but this has made no difference for my TPlink C80