easiest fix is to first split the circuit add a breaker. then find if
the old part or new part fails again.

in any case the time to troubleshoot it is when its failed.

for such a $^%$ makre a drawing of what feeds what starting with the
breaker finding the first outlet in the string. use ohm meter with
power OFF

once you have a complete map, the next time it fails you check each
outlet looking for where its first out

you electrician may believe its a neutral failure, but taking apart
each box is probably the first step