Boot waiting for network

Troubleshooting
1

I want to use my RaspBerryPi 3B+ with dietpi on it as a local server and a wifi access point, WAN-connected to an LTE router.
I successfully activated the wifi hotspot.
Now, two problems arise:

  • when at boot time the network wasn’t available, and later comes on, dietpi stays offline. How can I make the WAN network available automatically as soon as it comes up? Plus as a bonus: get the NTP time as soon as WAN comes up?
  • when at boot time the networks isn’t available, the boot takes about one minute longer. The boot messages say Job ifup@eth0.service/start running (##s / 5 min 2s). But it doesn’t take 5min 2s, it takes about 1 minute (which is bothering enough). Can it be configured to a much shorter timeout, like 5 seconds? I already tried what Jolinar wrote here, but I have no /DietPi/dietpi.txt. I put it in /boot/dietpi.txt, but that doesn’t make a difference. Also, in dietpi-config under Advanced Options I have Time sync mode : [Custom] and under Network Options: Misc, I have Boot wait for network : [Off]. So why is the boot process waiting for ifup@eth0.service/start anyway, aren’t these settings suppose to eliminate any waiting?
2

sounds similar to this one Wired Ethernet on Connecting at Power-Up on Raspberry Pi 3 - #37 by MichaIng

3

Thank You for pointing me there. The last post (disabling Ethernet Energy Efficiency mode) didn’t help.
But setting a static IP address (Wired Ethernet on Connecting at Power-Up on Raspberry Pi 3 - #17 by MichaIng) helps, both with the long waiting time while booting as well as going online later, if at boot time the network was off.
Thank You!