Apologies for jumping in, another factor to bear in mind is that micro SD cards have a limited life, there are records on the forum of failures of cards in RPi, DSLStats service, usually quite drastic, program won't boot or such, just a thought ?
Running DSLStats to MDWS involves quite a heavy shedule of reading from & writing to the SD card which can reduce it's life span considerably.
Ref. the Billion 8800NL R2, I bought one S/H from a forum member for use on my daughters PN VDSL line to replace her PN Hub One which has very limited stat's provision capabilities, very pleased with it's performance, running DSLStats on a RPi Zero W to MDWS, her ID is "cruth211", not a very good line, lots of noise but can't fault the router.