LilyGo T-Eth-Lite problems (bis)

[simonjo]

I built around 40 domotic controllers with the Lilygo T-Eth-Lite (using RTL8201) over the last year and in the last batch of 6 modules I have 2 modules where the Ethernet connection does not or not always work. The previous batch of 10 modules also had 2 non-working modules.

So 4 modules that have an ethernet problem while the other 36 modules work just fine, with the same firmware, same hardware design.

What I notice is that the ethernet interface does not get an IP address, when I pull the network cable and reboot the module 1 or 2 times, then plug in the cable and reboot it again... it might work and the ethernet interface gets an IP address.

Here you see some logging where the ethernet interface is started and sees the cable, then the cable being pulled and reinserted, but an ip address is not assigned
>>>
2026-03-06,21:39:22,I,NETW,>Starting Ethernet
I (1800) esp_eth.netif.netif_glue: c4:d8:d5:6c:d2:13
I (1800) esp_eth.netif.netif_glue: ethernet attached to netif
2026-03-06,21:39:23,I,NETW,<Ethernet link up
2026-03-06,21:39:45,I,NETW,<Ethernet link down
2026-03-06,21:39:49,I,NETW,<Ethernet link up
<<<

This is how it looks on a working T-Eth-Lite
>>>
2026-03-06,22:44:26,I,NETW,>Starting Ethernet
I (1849) esp_eth.netif.netif_glue: 24:dc:c3:07:d0:93
I (1849) esp_eth.netif.netif_glue: ethernet attached to netif
2026-03-06,22:44:27,I,NETW,<Ethernet link up
2026-03-06,22:44:29,I,NETW,<Got IP address 192.168.0.100
I (4949) esp_netif_handlers: eth ip: 192.168.0.100, mask: 255.255.255.0, gw: 192.168.0.1
<<<

Found an EspHome issue (https://github.com/esphome/esphome/pull/6704/commits) with these RTL8201F chips where they found a floating pin to behave different depending on the production date code of the chip, upto date code M was working fine and after that (N, O, ...) it failed. They have a solution to this by setting the clk_dir bit to 1 in page 7/register 16.

So I verified the date codes on the working and non-working T-Eth-Lites... helass, I found date codes N and O both on working and non-working modules. I also made a patch for the ESP-IDF RTL8201 driver to try the clk_dir solution -> but it did not solve the issue and actually worsened the problems in that no IP flow occured with the patch (the webinterface did not show any pages).

The boards work fine with Wifi but ofcourse that is not the intention.

I added the schematic below, can anybody give me some more hints towards a solution?

[simonjo]

T-ETH-Lite-ESP32.pdf

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