If you regularly use a lot of your 200/200 Internet service then a RPi 3B+ won’t cope. Nevertheless, it has been a good learning curve for you with IPFire.
AFAIK, RPi 3 series still put onboard Ethernet through the single USB bus, so onboard plus your USB Ethernet dongle are sharing 240 Mb/s effective throughput, resulting in 120 Mb/s maximum for each - less in practice, because other devices, such as SD card are also sharing the USB bus. Putting high data rate from the Internet into a slower Ethernet device could produce the data loss and ping delays that you are observing
A Gigabit USB Ethernet dongle won’t help - it would still be constrained by USB throughput plus Gb dongles tend to chomp 500 mA, which is a lot for a RPi.
In short, if you need anything approaching 200/200 then you need to set up an x86_64 box for IPFire
NTP & Ping
I built up a RasPi 3B+ with Core 138 (2.23.2gb-ext4.armv5tel-full-core138) and NTP seems to be working A-OK for me. If I go to the console or terminal I can enter date and get the correct time.
And pings work as expected. I can ping google and many others.
Ethernet LEDs
The green LAN LED indicates the RasPi 3B+ is connected to a 10/100mb network connection and blinking LED indicates data transfer.
The amber/orange LAN LED indicates the RasPi 3B+ is connected to a 1000mb network connection and a blinking LED indicates data transfer.
@aesenn - I owe you an apology for sending you bad info. The RapPi 3B+ on-board LAN is Gigabit Ethernet and it tops out at near 300 Mbits/sec. I’m trying to locate some technical info on it.