I use Android of various versions and vendors: i.e. Samsung Galaxy S4 with 4.4.4, Xiaomi Redmi Note 3 with 6.0.1 and others.
I found some faulty behavior of an application only when using LTE and it ended up with IP packet fragmentation.
To test my findings I ping 8.8.8.8 with various sizes:
ping -s 1200 8.8.8.8
works just fine
ping -s 1800 8.8.8.8
works only when using WiFi. 2G, 3G and LTE fails.
Is it a carrier bug, Android bug, or is it by standard?
This is from the 3GPP TS 23.060 V14.3.0 (2017-03) :
"According to clause 9.3 networks can provide link MTU size for MSs. A purpose of the link MTU size provisioning is to limit the size of the packets sent by the MS to avoid packet fragmentation in the backbone network between the MS and the GGSN/PGW (and/or across the (S)Gi reference point) when some of the backbone links does not support packets larger then 1500 octets. Fragmentation within the backbone network creates a significant overhead. Therefore, operators might desire to avoid it."
So it is not really a standard nor a bug, it's the decision of your network operator.
Ref: https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=758