I have had a Peplink Balance 300 for many years. The firmware is v4.8.1 build 1259. It has been very reliable until recently.
About 4 months ago, I started to add many (40) Inbound Firewall Rules to combat intrusive web requests from China, Russia, Korea, etc. Now, every time I reboot the Peplink Balance 300, I have to upload the saved configuration file otherwise it does unpredictable and erratic things.
Also, on occasion, at any time of day, it starts to act erratic also. Again, I upload the saved configuration file and it works fine.