It's taken me two weeks to figure out that the cause of:
Oct 08 01:25:35 FIDOPOLL Version 1.12 A35
Oct 08 01:25:35 Scanning 21:1/145
Oct 08 01:25:35 Queued 0 files (0 bytes) to 21:1/145
Oct 08 01:25:35 Polling BINKP node 21:1/145
Oct 08 01:25:35 Connecting to 10.0.0.21:24556
Oct 08 01:25:35 Connected
Oct 08 01:25:35 Authorization State: 1 HH:0 NH:1
Oct 08 01:25:35 Sent: NUL SYS AlphaTest
Oct 08 01:25:35 Sent: NUL ZYZ bcw142
Oct 08 01:25:35 Sent: NUL VER Mystic/1.12A35 binkp/1.0
Oct 08 01:25:35 Sent: ADR 21:1/145.2@fsxnet
Oct 08 01:25:35 Invalid data frame
Oct 08 01:25:35 Recv: Data 8/16,972
Oct 08 01:25:35 Authorization State: 2 HH:0 NH:1
Oct 08 01:25:35 Remote disconnect
Oct 08 01:25:35 Authorization failed
Oct 08 01:25:35 Scanning 80:603/0
Oct 08 01:25:35 Queued 0 files (0 bytes) to 80:603/0
Oct 08 01:25:35 Polling BINKP node 80:603/0
Oct 08 01:25:35 Connecting to 10.0.0.21:24556
Oct 08 01:25:35 Connected
Oct 08 01:25:35 Authorization State: 1 HH:0 NH:1
Oct 08 01:25:35 Sent: NUL SYS AlphaTest
Oct 08 01:25:35 Sent: NUL ZYZ bcw142
Oct 08 01:25:35 Sent: NUL VER Mystic/1.12A35 binkp/1.0
Oct 08 01:25:35 Sent: ADR 80:603/0.2@retronet
Oct 08 01:25:35 Invalid data frame
Oct 08 01:25:35 Recv: Data 8/16,972
Oct 08 01:25:35 Authorization State: 2 HH:0 NH:1
Oct 08 01:25:35 Remote disconnect
Oct 08 01:25:35 Authorization failed
Oct 08 01:25:35 Polled 0 nodes

From AlphaTest, my .2 test point was caused by filezilla being used on the
ftp part of my main Hub (Mystic Pi BBS at bcw142.zapto.org). The filezilla caused an entry in badip.txt for the system, but the error message:
Oct 08 01:25:35 Invalid data frame
Oct 08 01:25:35 Recv: Data 8/16,972
Doesn't really give me a clue that is was BLOCKED or in the badip.txt which
it was and that's what was causing the Invalid data frame with the weird data of 8/16,972. I think it needs a clearer error message when something is BLOCKED, like maybe the word BLOCKED.
Miner issue, just a confusing error message in A35 for both Linux/64 & Windows/64 versions (and likely all versions really - I just tested those
two on this dual boot system). You might also alias ls for dir in the ftp server as well, I'm used to using ls not dir to get that data and so was filezilla and a number of other ftp clients. That might make it more
compatible with the ftp clients (I quickly adjust but the clients never do). Again a miner issue that makes for a little confusion in A35 (and before).
In the process I did try telnet and binkp on both mis and mis2 in all combinations and found them to work the same. I am generally using mis2 for telnet and binkp on this Linux/64 setup. When the hacking gets too great I add in iptables to block the areas the problems are from using the data from http://www.ipdeny.com/ipblocks/data/countries/cn.zone for china and so on. I have found iptables in the versions of Linux I use for x86 & Pi so substitute that for badcountry.txt when using mis2. I haven't found a single script I
can use, but have made two that do it that I need to automate a little
better. I have the countries manually added to the script and should parse
the input line for the country codes and do it from there. I suppose parsing data/badcounty.txt would be the best way so it would work as much like mis as possible and add it as a startup event making it mirror the mis method.

--- Mystic BBS v1.12 A35 (Linux/64)
* Origin: Mystic AlphaTest bcw142.zapto.org:2323 (21:1/145.2)